I wouldn’t use the OEM jack at all, it’s dangerous on a vehicle this big.
I carry a bottle jack which has less stroke than the OEM scissor jack, I also carry aluminuim plates to spread the load on soft ground plus a plywood spacer to drive over first to get the jack under the van with a flat tyre. You have to measure and experiment with what works for your wheels, tyres and suspension. Remember to allow for suspension sag as the axle is unloaded and the drop from a deflated tyre.
It’s pretty hard to sort out with standard OEM set up let alone lowered with body mod’s.
Better to have a plan ready before you really need it.