Well!!! AN interesting dilemma of questions! Once again, the UWP rears its head and demands an answer--this time, based on astrography of the region, and the tech levels of the powers that be in Gateway Sector...
To be of some service---page 147 of the Gateway book: "each system in the gateway region is identified by its mainworld, and normally the UWP refers to this world. However, the UWP is just the merest beginning, a broad generalization of the broadest sort."
Meaning a lot of things, gentlemen--namely, don't take all of those numbers for granted!
IIRC Alphaaric is the highest tech level world in Gateway-(TL-F), and is homeworld to the Faar minor race. Yet ,"the Faar have no interest n building starships of their own" (page 98 on pdf)--yet we see an A-class port there. The population given is for the 9,000 some odd humans who dwell/ work there, not the Faar themselves! So who is making starships of TL-F quality and components there? HUMANS!
At Akeen, the 1 million inhabitants listed in the UWP are in the huge orbital A-class TL-D port named 'Sky'. Those are TL-D starships built there, or their components for sale! again, by HUMANS..Akeen technology is approximated to human tech planetside!.
Now interpreting Tech levels "straight across the board"... too simplistic. Lets look at the warlike Hochiken's Peoples Assembly:
The highest TL found on their worlds is TL-B, at Valkyr (1709), which also shares the highest Law level (E) with GRANTH (1601). Could it be, in rimward Valkyr, the rulers of this ironfisted government make jump drives, but not the starships themselves to prevent anyone from defecting by stealing a starship offworld? Say manufacture them here, and install them in any of the more secure A-class yards to corewards ie-SHANEYFELT [1904], Klavien [2003],Therinth [1501], or GUNTAR [1101]?
Another thing to consider of the UWP's--it is assumed that is the tech level the average citizen enjoys living under. So What if the TL-B enjoyed [at law E of course!]of the citizens of Valkyr is the"average"? Wouldn't the orbital starport's inhabitants enjoy a higher one? OF Course they would! But because they aren't the majority/ this goes unnoticed on the UWP!
Another thing we have seen, this in the EPIC adventure "Merchant Cruiser", the world targeted in the adventure for trade has a C-class starport, the non-aligned main world's primary one, yet in the adventure, it lists they have built their own TL-A SDB's--which all of us know requires a B-class shipyard, right? What if the world possesses several starports, being high population, right? Say it has six for example--five of them are Type C, one is type B. The more numerous one is counted, isn't it?
Or if said B-class port is on another planet in the same system--it isn't listed on the "mainworld's" UWP! You see?
Now I admit, making a strict TL-A Navy and commerce fleet for Gateway Sector would be a challenge--multiple J-1 tankages would be necessary. this would cut down on weapons, troops, and cargo tonnages. And Looking at a dispersed polity like the HPA, it would tend to slow down their expansion somewhat. With a lot of two and three system clusters, the coreward ones rather dispersed, it would be a chore to try to keep any sort of unity.
Hence I think the HPA keeps its J-2 technology for the military rather tightly controlled. And "Free Traders" don't exist within the HPA--that's a HPA state run commerce system!
Now looking at the THB's starship design pages, planets with TL-7 through F contribute components for starships in Traveller. Looking at some of the standard design sequences ships in there, I see a lot of power plants at TL-9.
Your next stellar polity--the Plavian league-threatened by the HPA to coreward of it:
It has four A-class yards with which to compete against the HPA's 5 with--Samuelson [2014/pop 700millions/ TL-A]; Bremen [1818/pop 9 millions/TL-A]; PLAVIS [2113/ pop 2 billions/TL-A]; and Tash [1513/ pop 400 millions/ TL-B].
--again, the higher technology exists, and is at Tash. They too can produce their own J-2 drives, and farm out th rest to the other four yards.
The Galian Trade Federation--Has one A-class yard, at 1220/ Gateway herself. TL-A, enjoyed by the average 6 million plus citizens. yet we know the GTF does heavy trade with the Imperium, and into Alpha Crucis Margin as well as the pirate scourged "Sardis Run" to the Megusard Corprate to trailing.
Here you can decide whether or not she imports all of her higher Jump drives/ powersystems/ computers, and weaponry or not. Certainly the HPA Valkyr model above can be translated to the GTF world of TAMERIJ [0430/ pop 4 billions/ TL-B]. After all, page 86 says Gateway's primary export is starships!
As for Messr Falkayn's postulation on Naval yards vs Civilian yards, I concur. Any world with a N Navy base has a seperate facility IMTU. C-class being the lowest class of port to maintain a navy base.
And as for Starmercs--one can always find them available in the Swanfei Free Worlds for hire! If you trust them, that is...<grin>
Looking at the TL's straight across the board, and some of the other worlds with higher tech within these polities, I have to go my route for MTU...ANy J-1 ships [even those with multiple tankage jumps] are going to be found working within the Gateway states, well escorted.
Outsourcing to the independent worlds of course, is an option..But there are few of those that can do what you need:
Alphaaric [1133] A996322-F 832 Xx
Akeen [2708]A66A620-D N Ni Wa Ak
Bem [3207] AADA330-C Ni 711 Xx
Banserda [3110] A512623-B Ni Ic 913 Xx
Grovelunda [3223] A439667-A 323 Xx
Vestra [2415] A23474B-A 402 Xx
Neopis [2020] A676789-A Ri 521 Xx
Far Portal [0130] A238546-A N 323 Xx
Caldwell [0332] A401654-A N Ic 323 Xx
DOVER [2423] A8999A6-9 Hi In 213 Xx
Trondelm [3137] A53A8A9-9 Wa 211 Xx
Emoress [3117] A66A779-9 Wa 410 Xx
Baker [0334] A876677-8 N 905 Xx
Inast [1210] A663669-7 N Po Ni 812 Xx
Whatever solution you decide upon, it falls to the imagination how to rationally explain it to your gamers and yourself. The UWP's are broad guidelines, that we've seen!
Sorry this took so long. Hope this helps somewhat.