those inspections may as well be at the starport -- both incoming and outgoing. Get to them before they leave.
There is a fundamental FLAW in the presumption you're making.

That FLAW is ... where else could that traffic go?
For
legitimate, law abiding parties, they're going to go to the starport ... where there's plenty of customs and inspections infrastructure in place to "handle the load" (depending on starport type, of course).
But what if a craft
DOESN'T GO TO THE STARPORT for inspections and checks?

What if a (streamlined, 2G capable) starship decides to make a landing "outside the wire" of the
downport jurisdiction territory ... thereby avoiding/evading ALL of the laws and institutions put in place to prevent the transfer of illegal goods to/from that world?
In any sort of "smuggling to evade local laws" circumstances, you need to have a customs and inspections system that isn't confined to the starport ONLY. You not only need a
Coast COACC Guard, you also need a policing system that extends into orbit and beyond in order to establish a "continuity of manifests" dataset that then makes it possible to process quickly through the starport (or land elsewhere on planet away from the starport, without issues).
Note that even rights to wilderness refueling could be restricted and policed, meaning you can't just fly your starship out to any lake/ocean and siphon up as much water as you want to (for free!) on some worlds with low hydrographics percentages, where water resources are "too precious" to let starships simply "gulp and go" with no recompense to the world's inhabitants.
My point being that "intrusions of illegal activities" (such as smuggling) are best thought of in terms of a disease framework, in terms of response.
Having a "crust defense" can work if there is only a SINGLE point of contact with the "outside" ... such as when ALL interstellar traffic MUST be routed through a
highport in orbit and NO interstellar traffic is permitted to land ANYWHERE on the surface, so ALL orbital transfers need to be made by locally produced (and inspected/authorized) orbital shuttle services. For this kind of setup, any kind of interstellar craft that attempts to make an unauthorized approach to the world for landing is immediately classified as hostile and will be attacked by local defense/policing forces (so don't even try).
However, if you've got a
downport and a
highport and there's lots of commercial interstellar traffic routinely landing on the world surface for wilderness refueling ... there's going to be PLENTY of opportunities for "illicit trading" outside the jurisdiction of the
Starport Authority (SPA) that can enable the transfer of illegal goods
and passengers in order to evade local laws (and the enforcement of them). Once the "points of contact" with interstellar commercial interests can no longer be confined to a single point of entry/exit, you're going to need what amounts to a "defense in depth" type of approach. There's going to need to be inspections both AT the starport(s) as well as a AWAY FROM the starport(s) to make sure that there isn't any smuggling of illegal goods going on. As soon as you get beyond a SINGLE point of contact with the "outside" ... you're going to need a "defense in depth" style of policing, with multiple layers, to ensure that local laws and prohibitions are being upheld.
Here's an example of how even a "routine wilderness refueling" type of maneuver could be used as a cover for a transfer of illegal goods by smugglers.
Guess what ... if a starship does a wilderness refueling maneuver before arriving at a
downport for inspections of cargo/passengers and details of shipping manifests, this kind of "illicit exchange using vehicles" becomes extremely possible ... and thus something that local law enforcement would need to monitor (in order to prevent).
In the "small package trade" (smuggling of less than 1 ton of goods), a
Speeder becomes something of an ideal option, since such anti-grav vehicles can make orbit in 1 hour. So rather than sending an entire starship down from orbit to a world surface for the transfer of smuggled illegal goods, you just send out a SMALL vehicle to slip through the sensor nets to make a fast run.
