There are many places here that make puppy sweaters.
As with most basenjis they will only go out in bad weather if you go with them.
You can always just carry her out with yourself in bad weather- our breeder did that with all her dogs, both puppies & adults- she was in charge not the dogs!
Luckily we live in Florida so we don't see too much cold weather. However, in the AM it can sometimes be a bit chilly so I have to pick up Dallas & carry him to his potty place of he will not step on the grass, same for when it's wet from rain/sprinklers. You are bigger than he/she is so be the boss & just move them. They'll learn!
Oh & I looked at that website & am in love with the argyle coats. I think I am just going to have to get it…although in Florida it might be a bit of a waste of money? :p