I would like the stiffen up the rear suspension with either air shocks or air lift. I seems to bottom out easily on speed bumps, also I want to tow with a 300# tongue weight. I see there is a cushioned filler on the inside of the rear springs preventing an "in spring" airlift. Has anyone found and air shock that may be fitted? I would like to stay away from the in between the coil cushions. Any experience or advice is appreciated.

Thanks.