Will this offset design work?

No different than a baffle plate I'd imagine. The metal will heat up and retain that energy.

yep.. should run like a champ.. the pipe is just taking the place of a standard U shaped baffle...

Sure, I've seen & helped with offset mods using pipe before: this one look like about 6" for a 20" diameter pit and thats not bad. It also it looks the right proportion (firebox looks about 1/3 of cook chamber). Looks like the biggest challenge will be heat loss the way that door works and he won't have the benefit of all that thermal energy stored in a heavy RF baffle plate. He will just need to learn to keep is closed up and get the fire right. Might also consider some kind of grease/moisture drain in the cook chamber - he does not want a pool of hot grease up against the fire box - it will ignite. Interesting build, I would like to know how it works out.

This is a similar design to the RF smokers built by Johnson smokers - www.johnsonsmokers.com - I have on order one of the patio models - very interesting setup - in his units, the rf pipe can be removed and a charcoal basket can be put into the cooking chamber for direct cooking

I think that I would take another look at the flanging around the sides of the lid but other than that it looks pretty cool!:thumb:

Cleaning up may be harder with the pipe than a flat baffle.
How will the grease dripping on the pipe react?
jon