Well, after some more research I've decided to hold off on the vaccines. Thanks y'all. I almost didn't even think about this being an issue!
There's not a lot out there but one thing that is consistent is that vaccines should only be given to healthy animals. I found one vet that said she doesn't recommend them for unregulated diabetics.
Since our potential beach trip is 5 weeks away, I'm going to try and get Skunky's levels better regulated in the next couple weeks and then reassess.(since we're only one week in on the insulin) And heck, I'm not even sure I'll be able to board her anyway. My vets office wouldn't be able to do a 12 hour dosing schedule because, on the weekends, nobody is even there from 5 p.m. til 7 a.m. Yikes!
She'll probably need to go to the vet sometime in the interim anyway, or maybe I'll be able to hit up another low-cost clinic.
I found one boarding site in California (i was just doing research) that requires the feline leukemia vaccine for boarders. Yikes! I've tried to get that a few times and the vet (different ones, too) have always talked me out of it!