I got a Northern Tool sale flyer in the mail the other day. Unfortunately there are no "Northern" Tool stores in the northern state I live in, but they carry a really great selection of stuff for trailer builders.
Here's something I hadn't seen before, they call it a "15-Gallon Fuel Station":
Here's what the catalog says about it:
The Hy-Pro 15-Gallon Fuel Station features a durable welded steel tank that can be used with gasoline, diesel and kerosene, minimizing repeated trips to the gas station. UN/DOT compliant.
Features + Benefits
- 15-gal. capacity tank has a 10-ft. hose with gravity feed design and efficient squeeze handle dispenser (fuel station must be mounted at a higher level than receiving tanks for optimal performance)
- Built-in shutoff valve prevents accidental draining
- Designed to bolt onto a trailer (hardware included)
- 39in.L x 12in.W x 15in.H
- Ground wire with alligator clip and internally grounded hose assembly for safety
It's listed at $149.95, which makes it less expensive than three 5-gallon jerry cans plus the mounts for the cans. Here's a link to it:
http://www.northerntool.com/shop/tools/product_200584598_200584598?isSearch=29578-1313
I haven't decided if it would be a good idea to replace jerry cans for fuel on a trailer with something like this, but here's a few superimposed images with the tank roughly the same scale as and M416-style trailer. The tank could mount either on the tongue outside the bed, or inside the bed (mounting it inside might provide some challenges for routing the hose so gravity feed worked well).
I don't plan to do this on any of my trailers, just thought I would post it here because it's on topic.