LOL!
Things with texture are good -- real wood branches/driftwood, etc. That's what counts as 'rough'. If something seems too sharp, it probably is.
I would absolutely not put in anything like a hamster wheel that has potentially moving parts. I'd also seriously question the utility of anything that's not natural in form or function (plastic hides are OK insofar as they're simulations of natural hiding spots; a hamster wheel/Spongebob statue/lego replica of the space shuttle/Chinese finger trap/etc are not). Reptiles that get stuck in anything will force their way out and either break the thing they're stuck in, or break themselves.
Best to look at potential cage furnishings and try hard to think of how a snake might potentially harm itself with it -- if it is possible, it is probable. A BP has decades of 24/7 of "idle hands", and has all the judgement of a toddler with a permanent sugar buzz and a bad case of the terrible twos.