You need a vapor barrier on the warm side of the insualation before the "dew point" line. If I understand the Aerogell will guarantee that you have condensation in the system and eventually that goo of life, and it's cousins. Doesn't Aerogell just allow water vapor to pass through until it condenses? Then, if it has venilation, it will eventually dry-out, drip, or whatever. If you have steam or hot-water pipes, it's not a cold water line issue that's the problem.

I would be careful about "insulating the inside of a box" -- the power of "cubing" is working against you. (if you take a 2'x2'x2' box it has 8 CF of volume. If you take-out 3" on all sides, it's a 5.36 CF volume (2/3rds of the original. I did this more agressively when our Sabre 42 (hull #4) didn't have enough insulation for our SeaFrost system to work efficiently. My wife reminded me that I got a small cooler for the price of a SubZero we called a refrigerator/freezer. We kept a cooler for the drinks.