It sounds cute but I don't think it's very practical! We saw some cute costumes for tiny dogs in the pet store the other day and one didn't seem to have any leg holes... I did wonder if it was for a snake, but it turned out just to be a weird design
I just posted what felt like a massive rant about taking pets outdoors but please make sure your pet is safe if you take him out. I don't know what sort of snake he is but I'd get paranoid about a bird of prey attacking or if he escaped. Plus I don't know if there are any diseases wild snakes could have left traces of? I admit I'd not an expert at all, I just get scared about pets out in the big wide world... a lot of the animals I've had wouldn't have survived long outside my house/their pen!