Would there have been any chance of using camouflage paint scheme on a TD during '44-'45 ? I haven't found any M36's with camo pattern.

With in my own knowledge camo wasn't terribly common on US armored vehicles, I certainly don't recall seeing any tank destroyers in camouflage other than white washes in US service. If you want a cool camo, and don't mind doing a post war one, there are some cool patterns for Croatian vehicles during the 1990's from Star decals...

I only saw one picture of an M36B1 in combat and it wad OD to the best I could tell.

I've seen pics of M36s with whitewash, but none with camo in WW2. They arrived as winter set in, and probably missed out on the earlier "black bands" phase of camo on US tanks. As for M36B1s (the Sherman-based TD), the only pics I have seen are plain OD, right near the end of the war when whitewash was no longer needed. Trouble is, there aren't many M36B1 pics to start with...