I think the string idea is very good. The expen also, as it would allow him to enjoy more time outside when it is comfortable. But the nearest Dollar Tree or similar store probably has a very lightweight piece of rope... I get 70 foot long pieces of clothesline that has no weight to it at all. Create a loop big enough to go over his head and small enough not to fall off too often, and it should provide a visual "leash" for passersby without any discomfort to the doglet. One less nuisance to deal with.