Yes, you can put 100% of your bonus into TSP, as long as you set it up before you get it. Another option is to reup in a tax free zone, then get the whole thing without taxes.
This cost benefit analysis needs to be factored in with a couple things
1) time in rate
2) money lost from not having BAH
3) "benefits" of being an E-5
1 year of BAH in norfolk is around 19,000 a year, tax free. Time in rate is worth gold as well.
My point is, yes, 60,000 tax free looks great, but if you are missing 20K from BAH, whats the point?