DiskDoctr wrote:
So other than Liquid Roof, what would be the "other coatings" that work?
The "building stuff": 
Liquid Rubber. Same composition, lower cost, no differences btw the two have been reported by users. Manufacturer have added the line that Liquid Roof is a "specifically formulated version of Liquid Rubber for moving vehicles", don't remember seeing it earlier :). 
And then, there are coatings like Kool Seal etc, those are basically thick paint, not liquid EPDM.
Yeah, on commercials videos liquid EPDM looks easy but it is dense and heavy, and some prep work and repairs might be needed before doing this. Still easier than laying down new "solid" EPDM membrane in rolls.