The weight of the van on the tires is a stabilizing point, just like your jack stands. Don't remove all the weight on them. If you have two stands and a bottle jack, deploy them under the frame toward the rear of the van, that is typically the lightest part of a van and most susceptible to wind caused motion.
You do drive the van at greater speed than 50 mph so those gusts should not be a problem. The wind may rock the trailer but it will be momentary.
I'm guessing from your situation that your health is now better and you are situated at a better place. I was following your other thread about needing a driver. Hope that all worked out OK for you.