Some thread lock tape and a towel. The tape should hold it snug and the towel can also come in handy should you actually have to use the spare tire and you need the towel to wipe your hands afterward!

I also agree with the gentleman about keeping the spare in place. God forbid you get a flat or blow a tire in the middle of nowhere. Going under 40mph for distance beats walking for distance any day and the 35-40 lbs shouldn't be a huge factor unless you're drag racing. And if that's the case, you're only 1/4 mile from help, worst case scenario.

Keep the spare; add a towel; use some thread lock tape. Don't set yourself up for more serious headaches down the road.

Daryl