Replying to Single or dub barrel for b-yard setup?

yeah so thats the question. its gana be 18-20 foor and have a perrtyy damn good amount of speed available. And like the problem is the grounf where the rails gane be may not be completely even so im scared if i make the dub barrel it might be laening one way or another and suck? And the other question is will a single barrel be to hard to slide as a backyard setup and do tricks on? Im a decent skiier but like no0thing amazing so i wana be able to learn and cheel and have fun with it without killing myself. Thanks