I have a 1998 Ford E150 High Top Conversion van that I believe is 7000lb.... I know F150 should have about 20# PSI in the rear air shocks unless towing or hauling a load.... But a 7000lb van is always under load... I just had a leak fixed and my shop set it at 100 PSI.... I'm wondering if this is OK or should I back it down a little bit?