Well, my first question would be why don't you wait until you get to TX, have the weapon transferred on a F3 to a TX SOT, then get it on a form 4 as an individual. As I understand it, getting a signoff in TX is easy, and you are always better to have it owned by you rather than a corporation. Certainly you'll have to pay a little more for the extra transfer to the TX SOT, but considering what you'll spend on incorporating and keeping the corp alive for as long as you want to own the NFA weapon, its peanuts. I would only incorporate to get an NFA weapon as a last resort. If you are moving to TX and can get a CLEO signoff there, that should be your first choice, even if it means a few more dollars in transfer fees and a little more of a wait. Once you (individually) own an NFA weapon, you can move it to any state where possession is legal (ie. you can go back to FL with it after a few years when your job in TX is done). You merely have to do a form 5320.20 and inform BATF that the move to the new state is permanent, not temporary.
If you are dead set on doing the corporate route in FL, you can temporarily move the gun to TX provided you get an approved form 5320.20 from the NFA Branch. Its the same process as if you owned the gun as an individual in FL. As a corp you can't do it permanently, unless you also incorporate in TX though. I think the maximum they will approve is 6 months.