Key West & Houston both have excellent access by road at this point. Puerto Rico (and other Caribbean islands) are places where help by air can really shine. Here's the problem:
Where to go *
from*? Puerto Rico is a looong flight from FL - this limits the # of roundtrips you can make in a day. SJU (main airport of Puerto Rico) is still VERY capacity restricted and a 337 will clog up the works. They can fit a lot more relief supplies on a 737 than a 337.
http://www.npr.org/2017/09/27/553918...to-puerto-rico
The other islands in the area tend to rely on Puerto Rico - so if you can't base out of PR, you'll have trouble. They started GA relief flights out of SJU after Irma, but they stopped them when Maria came and they haven't restarted.
My local Angel Flight was collecting names & numbers of pilots who could help. If you're a member of PALS, Angel Flight, etc contact them and they'll steer you the right way.
I'll be down in FL next week with a 340 (up to 1400lbs, up to 800nm - but not both). If you're still flying then, post here and I'll join you for a day or two.