In September I installed reflective insulation around the lower section of the van. This will all be covered (out of sight) when the bed and cabinets are in place, but will have additional reflective thermal benefits.
With water leakage being a main concern, I would sit in the van and watch for leaks/ moisture accumulation during heavy storms. Thankfully the fiberglass roof never showed any signs of water penetration, but I did find a few small droplets coming from two of the side windows. As a precaution I used some silicone sealant on the tops of all the windows, and have since had no water leaks/ droplets during storms.