I don't know your monetary situation, but for one, you could get a shop to make a rear bumper/tire carrier....have an integrated hitch reciever (that makes it the most low profile and makes it less likely to get hung up on) with a swing out spare tire carrier. This would be my best bet, as it solves the issues without any real issues, and if you don't have an issue with having to swing out the tire carrier, its a great choice (doesn't take any space in your cargo area, and it looks good)
Another option, is go with the regular style hitch and bumper, and get one of those spare tire hitch mount things. They work I guess, but they seem like a real PITA to use-
1- Not sure how you get to use your hitch if you are using the spare tire holder 24/7
2- Depending on the design, it may be a BIG pita to get into your rear storage
3- Not very attractive
4- Low hanging hitch
5- Probably about %50- %70 the price of the bumper/hitch/tire carrier combo....
Someone already got a custom rear bumper/carrier on a r50, and It looked pretty darn good if I remember.......