I hate laying on my back, too. So here's what I do:
Park the tractor in the middle of the lawn.
Dig a REALLY big hole under the mower deck.
Stand up under the mower with a hose and scraper to remove debris.
In the mean time, the hole has filled up with water.
This is really handy, because I then can swim out of the hole.
Wait for the water to evaporate.
Fill in hole.
Put tractor back in garage.
Plant new grass seed.
Repeat frequently, as per Wheel Horse instruction on the dash board.
I Hafta agree with savageactor7 pull the left side over some standing water and set for a minute or two, it works kinda like a blender... Be sure the exhaust side is downwind or you will have a REAL mess to clean up.
Because we mow so much I cut a little bit every day so it doesn't become a pita project... even soaking wet grass.
Every time I finish I flush it out with puddle water. Here a pic of my deck after cutting and flushing probably a dozen time or more. It was more or less perfectly clean except for the grass stuck to the grease that gets thrown out from the bearings. And that grass doesn't effect the good discharge needed if your gonna cut wet grass.
If you gonna try puddle cleaning for the 1st time all you want to do is shave off a 1/2 inch or less of water at full throttle.