I've planned on burying my winch for years, the only reason mine isn't buried is because I lack the time, skill, and equipment to do the job at this time. I've actually planned it all out and will do it when I can.
I really like my free bumper (Loose Nuts Enterprises makes good bumpers, I won it at a raffle), it has a great shape but it sticks out pretty far. I don't consider this a design flaw because it's the nature of the beast. Being made for a consumer market you cannot expect run of the mill consumers to do extensive modification.
My goal would be a bumper shaped very similiarly to the current one but stick out no further than an OEM bumper (+/- 1"), that would be VERY nice for angles!
As for the cooling issue I'll evaluate that when I have it going, if I find it an issue it can be easily corrected with some heat sinks on the motor and a small muffin fan over the sinks.
As for mud/water I will protect it as best I can. I don't like mud and living here in California don't come across it much.
The clutch question is the most valid of all, I'm still thinking about that one.
Here is the Loose Nuts bumper with my M8000:
As you can see I still need to move the solenoid box under the hood (in fact I will probably make a new one in a more convienant shape), right now it's zip tied to the grill; had to get the Jeep ready for an event and was in a hurry