Our cold natured one wears her regular sweater and gets under the cover and that solves the problem. Looked stupid the other day when it was 70 outside and she had a sweater on.
Sorry, I've not seen anything like you're describing.
Susan

My gd little yorkie has a skin problem and is always scratching.To keep her from scratching herself raw,they put the babies outgrown onesies on her.So maybe you could find a one piece babies pj's to put on him. Look for one at the thrift store if you don't have a baby nearby.
Kathi

T-shirts. They come in all sizes. I have to buy for length but then the girth is too big so I take it in on the front. That helps bring the 'human sleeve' into a better position for the dog's legs.

I found a old Butterick Pattern yesterday at the Thrift Shop while looking for old t-shirts I measured and the pattern will be to small for him so what I did is I measured him length and girth and adjusted the pattern and made my own pattern the good news is I have the thing all sewed together except for the back legs and so far it fits him. When I finish I will send a picture of it for you guys to see. I do thank you for your responses.