My question is will this be worth my time if i plan on doing a Roth conversion ladder on all this money in 12 years when i hit 20 and retire? Or should i just concentrate on contributing the most for both years for tax return purposes?
Yes.
If you're gonna deploy to a combat zone, that's the way to do it.
Keep in mind that your annual contribution limit to the Roth TSP is $18K no matter where you're stationed. Your total limit for contributions from combat zone tax-excluded pay is $53K/year, so you're absolutely right that you could try to stuff $18K in your Roth TSP (both years) and another $35K in your traditional TSP (both years).
One downside to this plan: I've heard rumors that the MyPay/TSP websites cannot raise your Roth TSP contribution above roughly 50%-60%, while you can easily raise your traditional TSP contribution to 92%. So your money may not end up exactly where you want it, but continue stuffing as much as you can in there and sort it out later with the Roth IRA transfer/rollover/conversion ladder process. You'll never find a lower expense ratio than the TSP, and tax-free contributions are always good. You'll be winning the retirement-contribution game in the third quarter, and now the only question is how high you can run up the score.
You may also want to consider deductions to the Savings Deposit Program... 10% APY for money in a federally-insured CD.
Are you interested in re-enlisting or signing a bonus contract? Payments made for additional obligations that are incurred in a combat zone are also tax-free, and they'll make a nice lump-sum contribution to your TSP account. I wouldn't extend your service obligation just because of the money, but if you were going to do it anyway then it's worth timing it around your deployment to the combat zone.
To everyone else who's admiring these great military benefits: remember that the OP is deploying to a combat zone. There's a reason DoD is being so nice. In my opinion, it's far better to contribute a "puny" $18K to a retirement account than to have to risk paying the price for the chance to contribute a studly $53K.