Can't help about bottle lambs, but maybe I can about blind lambs.
A Shetland ewe here had a single blind ewe lamb a few years ago (the ewe herself had only one eye but that was unrelated and it's a different story

) Once we realised the lamb was blind (she ran away from her dam every time she was approached and was quite scared) we penned them up together for a few days. The lamb wouldn't feed when outside and I was worried the ewe wouldn't cope even in the pen. We left them overnight expecting a dead lamb by the morning but she was up and bouncing - unfortunately smack into the pen sides which made us all wince. After a couple of days we put them outside together - lamb stayed close beside her dam and the dam soon became used to her lamb's funny ways. We thought she wouldn't join in with the lamb wacky races, but she would put herself right in the middle of the group, so she could hear lambs all around her, then run as fast as they did. She did occasionally crash, but mostly she was ok. Once she grew a bit older the ewe would wander further afield to graze, and the lamb would follow her scent trail to find her, if she wasn't calling - this meant that even if her dam was only 20 yards away, the lamb would take a wiggly route to find her. Eventually she was weaned and continued to find her way about but a couple of years later her dam died. I felt sorry for her as she was now lonely, having relied so much on her dam. So we put her to the tup

. When her lamb was born we had the reverse of her own birth - she would butt the lamb if she went straight to the udder, so the lamb learnt to bump the blind dam's chest so she could smell her, before going under to feed.
From this you'll see why I think it's going to be very difficult for your little lamb to manage completely on his own. I don't suppose you have a motherly bitch you could pair him up with? Or foster him onto a ewe with a single - any more to lamb? Even then, I'm not sure how he would cope as one of twins - I would expect the new ewe to reject him too, as not being worth an investment of her time when she has a healthy lamb to rear. I do think it would work to keep him with you in the fields when you are working outside, but he will be quite stressed on his own in the shed - which is of course why you want to get him out. Maybe a radio playing quietly and an old sheepskin or towel to snuggle up to would help. It could well be that he will join in the wacky races once he's a bit older and make friends with some of the other lambs, but you would need to keep a close eye on him, and check at night that he wasn't left on his own. Our blind lamb took longer to learn her way around than normal lambs, although she did eventually.