Shouldn't be a problem. You are not raising the rear by raising the front. We have the glide rite system. It has a ride height control valve which increases or decreases the pressure in the bags to keep the ride height set as load is added or removed. My guess is that the VB system works in similar fashion. You should be able to level out the van by adjusting the linkage to the valve.
WARNING: Be aware that it is very unsafe to work on an air suspension system without first supporting the weight of the vehicle on jack stands. You can be crushed to death if there is a loss in pressure. It is unsafe to even crawl under a vehicle with air suspension without first supporting the weight. If you accidentally knock off a fitting or the system looses pressure then you can be crushed to death.
Not likely that you will run out of bag travel. If so then maybe some shims under the bags would be needed. But that would be fairly easy to make/install.
We monitor bag pressure and system pressure with a dual sweep gauge on the dash. Our bags are running at about 60 psi.
All the best,