I had a tolex cab with a shuttle and it would vibrate off when the cab was tilted. I looped the speaker and power cables through the side handles and around the front corners to keep it from happening.
I'm debating on adding a tilt back to one a couple of cabs I have. But I have found that placing a 1 or 2 inch notebook under a cab works very well.
If it's a carpet covered cab, a couple strips of velcro on the bottom of the amp works. Rubber feet that are softer rubber, not really hard, grip pretty good and will stay put on some degree of angle.