We normally rummage through the trash for a liter bottle for rinse water. Throw that on the dash of the truck and you have a warm water post dive shower. Great advice about the softside cooler.
Buy one bottle for drink water and refill from the tap. The night before fill half way and freeze, then fill the rest in the morning and you have cold water between dives. Do remember that Bonaire is three miles from the sun and it can eat your lunch if you're not carefull.
The other standard advice for Bonaire, bring money, humor and patience, spend the money, share the humor and practice the patience.
Will be curious to hear how the diving is there now. When we were in Aruba in January they'd had a lot of rain, water was about 10 degrees colder than usual and really strong currents on some dives. I and several others got "blown off" the Jane C when I went above the open hold. A lot less visibility too.
Lots of folks were hunting lionfish, so it that interests you take a spear. Still plenty to harvest. Sue