How do I install horizontal propane tanks in my Lance 1161?

I managed to get accurate measurements for the propane compartment today:

25.5" tall

25.5" deep

12.25" wide

The width might be a problem as far as using the ASME tank with the side mounted valve, gauge, etc... especially if they are mounted on the side of a 12" diameter tank.

I need to actually see the tanks that I'm interested in.... to get accurate measurements.

I don't see any advantage to using the 30# horizontal DOT propane tanks that must be filled in a verticle position.

Thanks for the additional input...

Chet