How could I add a warmer box?

I just bought my first trailer smoker, it's old and funny looking but the old guy I bought it from says it's a gem...we'll see!
I'd like to add a warmer box, and seal the lids (they leak a bit) any ideas as to how I might add a box on this configuration?

I would appreciate any suggestions as to how I might improve what I've got here!
Great forum, and thanks for all the info!!

BTW...the smoker is much smaller than it looks in the pictures. The meat chamber is 20"x48" and the fire box is 16"x36" lined with one inch fire brick.

SmittyJonz said:

Can u weld? Add a box built around the exhaust pipe.

Click to expand...

I was thinking about that, but not real sure how to design it..I will try to find some pictures of ones done that way...if they exist!