Tug,
Nope, I haven't bought them yet. I made a mockup based on Moeller's shop drawings just to test things out. I'm planning on a gunwale about 10-inches wide to accommodate the tanks and below-gunwale storage lockers aft of the tanks and forward of the lazarettes; the gunwale would remain about 6-inches wide from the cabin aft for about 2-feet for entry/exit.
About mounting the tanks, I've read about it but haven't talked to Moeller as yet about how their mounting straps would work in this configuration. Sounds like a task for today. I am planning on glassing in a couple of two-inch half-round stringers to house electrical, propane (not together), steering and control cables, etc that will run from the cabin aft into the lazarettes. Below the tank, extra material will be added to the stringer to widen it a bit to provide some support for the tank and likely will be the bottom attachment surface for the straps. I've been thinking that at SS T-nut epoxied into the support surface might do the trick, but have to look into the details.
T