RE: Dumas Swamp Buggy
The BSB will be alright with your 40.
The fuel tank under the engine works great with a exhaust pressure system.
The 40 will be on the light side , but it will make for a great fun machine.
The BSB is a little more difficult to build as it is a tunnel design.
It is a very durable boat and forgiving for pilot errors.
Good Luck and happy building.
Having this much fun must be illigal