God, I do so love the Eagles, they are like the quintessential Modular Cutter. I also really do love the Paleo-proto TU, although I did mean it about it being a Comedy show, can I use it for MTU, as such. I dig the Ritual and Tradition.
Take it and abuse it as you will. While all the stuff about uranium stokers and cocked hats isn't my usual serious universe, the beat to quarters, middies on deck, and scouts in cowboy hats is true. Since I'm not hampered by the OTU I drew all my inspiration from sources like Kipling, actual military traditions, sci-fi authors like Pournelle and Drake, and a lot of "that sounds cool" bits.
So the Imperial Main Fleet Navy is TL-15 and has a strong RN feel to it, but the lower tech (10-13) Colonial Fleet (the one patrolling the edge of civilization) is more like the American Gunboat, or Brown Water Navy. Less formal and rigid, more can-do without getting all the forms filled in first. A lot of the reason for the split has to do with the role nobility plays in these branches: you can purchase a commission in the Imperial Main Fleet, and it has all that that sort of thing implies. In the Colonial Navy you just better be good at what you do to gain advancement, and the nobility doesn't much enter into it it since it's a service that is looked down on as ungentlemanly.
The Scouts are kind of like the US Cavalry all the way up to the modern day, and they have all the imagined rituals and traditions ("Gary Owen", cowboy hats, and all that), including the ones that got crossed-over from the future-Russian colonists like cossack dancing and horse racing with much saber swinging. The internal rivalry between the two groups is useful sometimes for adventures and rolling up characters. The Scouts are as much a serious military arm as they are just exploration.
The Marines all look (and too often sound like, but that's my fault) like they'd be right at home at Rorke's Drift or Kyber Pass - red tunics, black trousers, white helmets, and lots of bagpipes. The US Marines morphed into the Colonial Fleet Marine Forces. Now the elite troopers, the Jump Troops; those guys are what the Foreign Legion turned into, right down to the kepis, nome d'guerres, and "March (Jump?) or Die" attitude.
But once in a while my players have over the years gotten too serious and over many drinks, and too much Gilbert and Sullivan on my part, we put together a "joke" universe of one subsector with cocked hats and walrus mustaches. I thought of just transferring it to Space:1899 when that showed up, but that game was too rigid and serious.