Impulse24......If you take a 5' tall road grader tire and fit it on your coach, please explain how more tire surface will make your braking better and the additional weight will have no impact. I understand you want something better, but you may be asking more of your coach than its capable of giving. If Yugo's road like a Lexus, they might still be around. I'm not calling your coach a Yugo, but the newer suspensions are more exotic and have 22 years of ride enhancement over your coach.
I would guess that a Trac bar would be your best bet for improvement. Try and find a 10' length of 2" square tubing. Insert it in your hitch and have a strong person push it side to side while you lay under the coach and watch your rear suspension. You may see it move all over the place. If it does, a Trac bar will probably give you some relief.
