Kay,
Our little filly Scarlet started out a lot like your colt. She was diagnosed as a dummy foal and although she initially appeared to nurse she really wasn't. She was running around just like your little guy for the first 16 or so hours. She also started fainting about 12 hours after birth. I don't know if you have the ability to do this, but I really believe the IV fluids are what kept her alive until she "got it." Your guy wouldn't have to be on it 24/7. The vet could come out and put the cath in and then every few hours you would hook him up for a bit. Just a thought.
Sending prayers!