Here is a pic of my rear pull type snow thrower - made in the '70s by Snow Machines, and similar to the Erskine pull type
This rig is really simple - one rotating auger/impeller - no chain drives, no gearboxes. For fluffy snow it can't be beat.
To answer your question about depth, it works best with 8" or less if the snow is sticky. The less sticky - the better it will flow, and greater depths work fine. Compaction is not too much of an issue - the plow edges get under it pretty well. Moving slow, the B7800 with FEL would handle it ok, power and weight-wise.
One place this tool really shines is on long driveways that have been plowed but need to be widened because the banks are getting too big to push back. By driving along with the FEL about 8 or 10" above the ground and about 2 feet into the snowbank, the snow spreads down in front of the tractor and then the blower comes along and launches it.
The Erskine units are a little fancier - with extending side wings.
While we're on the subject of pull-ahead rear-mounts, Pronovost has a combo backward/forward design that is great to watch in action - there's a video at their website.
http://www.pronovost.qc.ca/videoa.html
Their big stuff is pretty serious machinery.
Take care - and have fun. Dick B