Loaded up the car and headed to Fla for Christmas. Luggage, supplies and 4 adults. Didn't think it was too bad until I bottomed out the springs on a couple minor bumps. Anyway the car now permanently sags in the rear. Is there any easy fix? Are there different sized spring cushions that can be installed? If putting in new springs is the only answer would using SEL springs give me some more load capacity but not effect the ride?