When load testing during the winter, I do plan to let it heat up my shop building (48 x 30). 
Looks like my breaker bank will fit nicely in the build in box:

Test fitted the contraption in the enclosure after removing the compressor and coil:

Got 4.5" of clearance from the bottom of the tube and the floor of the enclosure:

I think that will provide enough air flow up thought the heater elements and I don't need to cut out openings in the floor of the outdoor unit, which was a concern I had.
Looks like my breaker bank will fit nicely in the build in box:

Test fitted the contraption in the enclosure after removing the compressor and coil:

Got 4.5" of clearance from the bottom of the tube and the floor of the enclosure:

I think that will provide enough air flow up thought the heater elements and I don't need to cut out openings in the floor of the outdoor unit, which was a concern I had.