My first concern was condensation. I decided to take to proper steps in order to prevent this, which I document here. I was planning on near-freezing CPU temps, if not sub-zero. I decided on closed-cell foam instead of Neoprene. The water-proofing ability may be a little less, but I believe closed-cell foam provides better insulation.
Closed-cell foam on the back of the mobo: Foam inside of the Zif-socket sealed with RTV sealant:
Neoprene gasket around the Zif-socket: Di-Electric grease inside of the pin holes:
In order to prevent condensation inside of the Zif-socket, I used Permatex Di-Electric grease. This may be a bit overkill, but it's better to be safe than sorry. Please note: Di-Electric grease is non-conductive. I almost made the mistake of using Gardner-Bender Ox-Gard, which after research, I discovered is conductive. If I would have used that, my motherboard and CPU would have been hosed. The dumb-asses at Sears Hardware told me this stuff is non-conductive. Good thing I sensed their stupidity from a mile away and researched it on my own :-)
One other precaution you may take is to spray the surrounding area with conformal coating. I believe my insulating job is adequate and therefore I opted not to use conformal coating.
Next, in order to maximize the cooling effects of the gigantic 50x50 TEC, I decided to use a copper shim. The Athlon core is so small, and it seems all of that potential cooling area is going to waste. This is a DTS-400 shim from CPUFx.