Sounds like you had fun outside of the cramping. I'm sure you've nailed proper prep for endurance activities in the heat - have you ever tried something like Salt Stick Buffered Electrolyte capsules? They have two versions, one with caffeine. I've found in serious heat it really helps to pop one periodically. They are on the large side, but well worth it.

Focusing on what you love without allowing it to become stressful is a great idea! It's so easy to go there without really realizing it...