What I'm about to say might take you by surprise. However, there's been a lot of plots that simply die recently because I think they need to consider this.
You should avoid using shared/used plot themes.
In the case of the 309th, it basically drowned your USO tanker idea due to most of the interest being there. This is also the case with how Alex, who wants to launch a mecha-oriented plot, is stretched thin between the spread of mecha players occupying other plots (such as the main 188 plot, Dig-It, and that one with the horny goat people). I think it's great people (including you) want to run these ideas, but these are far more niche plot themes than the mainstay that is copied between all of Yamatai (AKA Star Trek bridge bunnies).
Were it up to me, I'd recommend you take the Exploration plot. However, if you want to do post-apocalyptic/colonization, I might have some words to toss your way. It's a fairly unknown fact that I've been working on and preparing a certain group of aliens for Dig-It's first world. The
Atsila aren't canonized/finalized yet (they haven't appeared because of this), but once the Dig-It crew leaves, there will be a group of colonists and these buggos trying to colonize a world that has half of it covered in nuclear, glass deserts.
If you want to work together on something (I'd be willing to Co-GM and help foster some of the work for it), then I'd be down for pulling out the ol' hype stick to build some swag up for you. But this all is, of course, up to you. I think the Colonization and Exploration themes are the best... and if you can make it work with a canon "post apoc" area? All the better, right?