Foamboard and Paint

I have finished first-coating the stands, and the lower ramps.  The upper ramps are almost completely second-coated.  See below:

 The paint is going on well enough, but I fear one gallon will not be sufficient once I get to the upper growbed.  The stands are extremely annoying with all their nooks and crannies.  But once painted, it will be done.  I am a bit concerned about the feet of the stands, and the lower slants.  For the former, the notion of water intrusion (as the porch gets wet during storms), and for the latter, I fear they'll "glue" themselves down to the floor after being there for 6 months.

I returned the two undamaged 1/2" foam panels to the home improvement store today, and procured two "blue board" foam sheets.  The key difference is: this foam board is extruded polystyrene (XPS), rather than the white expanded stuff I had purchased previously.  The foam is much denser, doesn't flake, and is reportedly waterproof.

I tried to get the store to order the 2" thick foam I needed, but to no avail.  It seems no one carries it.  I even tried looking for DWC suppliers, but again came up dry.  I'm really at a loss to know what people use, if they don't use completely inert Styrofoam.

Not all is lost, though.  I purchased enough XPS to experiment, and ordered a specific adhesive from the local box store's website.  The adhesive is called Eco-Bond, and reportedly (for the "Farm-Safe" variety) is completely non-toxic, hypo-allergenic, etc etc etc, no evil chemicals, no distillates, waterproof, etc etc etc.  Certifications abound.  Seems too good to be true, but we're gonna give it a try.  Worst-case, I'm out $13.  The goal will be to laminate two or three (or maybe even four) sheets of XPS together, to form a decent DWC raft.  I'm still undecided whether or not I should pre-drill or pre-mark the hole locations, and then glue around them, or else just clue the whole board with lots of beads of glue, and hope I got good enough coverage to avoid splitting during use.