[Richard]

Would think that stacked bags would act the same as the separate coils on my coil over shocks. Each spring (or bag) sees the same amount of weight. For example my stacked 250 lb springs would compress 1" for each 250lb of weight. 1000lb weight each spring will compress 4". Total spring height for both springs will reduce by 8". This method effectively reduces spring rate by half. Have a 125lb spring rate. Changing spring rate in one spring will just raise or lower the effective spring rate (raising or lowering pressure in one bag). Some coil over shocks such as mine have stops for one spring. I can set the point my spring rate changes from 125lb to 250lb by stopping movement of one spring. You would need to stop movement of one bag at a point to increase spring rate. Bottoming out one bag would accomplish this. FWIU stacked bags would decrease spring rate not increase it.