Finally managed to finish my first deposit bonus ($93) at Tower, just 2 days before the deadline. The shortstacking at NL25 and NL50 tables worked very nicely right up to the last day, where in one session I won $20 in about 15 minutes, and then in another I lost $50 in pretty quick time.
I know many will say that shortstacking at too high a level can be suicidal, but in view of the way the bonuses work at Tower, I believe it was a reasonable strategy for me. Hopefully I can start to play with a bit fuller stacks at NLH now.
All in all it's worked out for me, and my balance is now $285. Now I pop back to VCpoker for a small reload bonus, and then it's time to find some value on a deposit of a few hundred.