I know I will catch some flack but here goes any way.... The thing that has worked best for me to keep the bugs away is a quick rub down with a fresh "Bounce" dryer sheet. For some reason the bugs are just not attracted to the scent left behind, but it is not nearly as offensive as some of the bug sprays (though the "cutter" products work well).
As for stopping the itch/burn of a bite: dip a cotton ball or q-tip in ammonia and dab the bite (same as "afterbite" active ingredient, just cheaper!).
For allergic reactions have LIQUID "Benadryl" in your kit. The liquid is much faster acting than the pills, caplets or melts. And if you are prone to allergic reactions check into having an epi pen.
btw, I live in a very mosquito and gnat infested area of Minnesota, have a daycare and HATE dealing with bug bites on kids. I used the same remedies when we went to San Pedro 3 times and to Jaguar Paw and Laminai.
It's great to be .....