The Roth TSP confused the hell out of me, so I got a bunch of advice from USAA's J.J. Montanaro:
Is the Roth Thrift Savings Plan right for you? | Military Retirement & Financial Independence
Ryan Guina also has good TSP & Roth TSP posts at The Military Wallet:
Thrift Savings Plan - The Military Wallet
You haven't brought it up yet, but are you getting a match on your TSP contributions? Are you maxing out the match before you decide about the Roth IRA and the Roth TSP?
Once you've maxed out the TSP match, and then maxed out your Roth IRA, you're ready to put more into the Roth TSP. I think you'll find that you have enough RMDs coming from the TSP when you retire (unless you roll to a conventional IRA and convert) and you'll also have your Reserve pension pushing you well into the 15% bracket... limiting the amount of Roth conversions you can do after age 60.
As for the TSP or conventional IRA conversions to Roth, when do you plan to stop working? Serious question-- you can probably only maximize the Roth conversion window before age 60 (Reserve pension) and after you stop earning a civil-service income.
Now let's make this even more complicated. Not only do you have a civil-service TSP and Roth TSP account, but you're going to start contributing to your military TSP and (eventually) military Roth TSP account again. I think you're still subject to the $17K/year max across all four accounts, but you'll need to check that with your Reserve unit.
You could make it even more complicated by doing your Reserve duty in a combat zone, which gives you humongous tax-free contributions to your military TSP account. Search Ryan's blog for more on that subject.
That gets rid of the RMD issue, but it also moves your investments from the world's cheapest index funds (just 0.025%) to more expensive funds (Vanguard's or Fidelity's 0.07%-0.10%). Might be worth the tradeoff.
Cheaper expenses, yes, but you lose the flexibility of being able to withdraw contributions from the Roth IRA... or to use some of it for a first-time home purchase.