I am designing a product that consists of a bare flexible printed
circuit board, some on-board chip components. The product is flat. I
need to find a way to "encapsulate" this product.

I want to product a product that would be similar in manufactring and
product like those flexible computer keyboards?
http://www.compusa.com/products/product_info.asp?product_code=309746&pfp=SEARCH

Here are the requirements:
Flexible: <= 70 durometer
Clear or high degree light transmission
Apply PSA (Pressure sensitive adhesive) to it or be able to put stickers on it.
Able to paint/silk-screen on it
Not harden/crack in UV light.
Able to be outdoor.

At first I'm thinking of a clear silicone RTV, but you can't stick
anything to silicone. Then comes a urethane. Can it be environmentally
sound?

I also am looking for a domestic (US) manufacturer/molder that can
take a bunch of these PCBs and overmold them.

Dow Corning (www.dowcorning.com) 182, 184 or 186 are clear, Shore A
50, silicone potting compounds.

Labels with silicone adhesive might stick to the silicone potting compound.

I don't know of any way to print on silicone.

i'm investigating urethane and silicone, and similar shore A types of
compounds. I think that once I find a molder that can do the overmold
or potting process I'll be set