Those that I have seen are not very heavy duty.
More or less the same 'guts' as walk behinds, only wider, just look at the gear boxes.
Better off to locate a standard PTO type and power it with a suitable engine.
I recall 5 hp per foot being the requirement, in fact I did power up a 48" with a 16 hp wisconsin using sprocket and chain and it performed great.
All that said, a rear mount is probably still the best solution all around, just learn to sit sideways as you blow.