How often do you go in and out of the garage? It might be easier to just take the cover off of the rear AC when you move the RV. The alternative is to let the air out of the rear tires and then reinflate them after you have passed the door opening.
Due to the rake of your coach, air bags MAY HELP if raising the front end will lower the rear end. This can be easily checked by looking at the location of the rear AC in relation to the rear axle. If it is over the rear axle, raising the front will not help. If it is well behind the rear axle, it may help and you can check this by putting a jack under the front axle and by jacking the front end up, you can measure how much the rear drops. I seriously doubt that the air bags will help your situation.
