I don't have any vacation ideas as I haven't had a vacation in, oh, I don't know how many summers due to my health lol, but if you aren't allergic to anything, I see a kinesiologist who is also a nutritionist and she has me drinking a container of coconut water every day. It is the most natural form of electrolytes that there is; I dilute it with water. I never got dehyrated following my colectomy even when I was having 20+ bms a day, except when I had c diff but that was something totally different. You can find it at Wegman's in the Health Food section or at a Health Food store.
Just thought this might help with the dehydration issues.
Take care and good luck with your vacation plans. We are actually plannings on going to see our daughter in Myrtle Beach after I get my stent out on August 11th. I' sure it will be extremely HOT but it will be so worth going especially after these past few months and the fact that I get I get to see my little girl .