Congrats on the weight loss! I turned 50 2 weeks ago and am on vacation in the Philippines for 1 month and biking daily (3-5 hours). My experience in the tropics is to get acclimated to the heat. Takes a week or two for the body to adjust, so try to ride daily to get adjusted. I rely on my camelback to keep a supply of water going. You may also want try hydrating a few hours before the ride. In any case, I always trust my body and take breaks if needed.