I wouldn't worry about un-even weight on the front. Does that mean you can't drive without someone in the passenger seat?
You can secure the load somewhat, keeping it from rolling back and forth I assume.
You could put your spare tire up there instead, like lots of trucks do, which would be in the middle and not move, but not sure how that works with the radiator. Must work with all those trucks that do that.
With the spare up front, you have more weight allowance on the back for a cargo carrier if that is the plan.
We carried a heavy box on the back of the truck with the receiver, but added two more receivers on the back belly bar each side so the box used three receivers to keep it steady. (Box held a Honda 3000--you knew it was there!)
You can do the math for weight on the front using the guide for snow plows on a truck. Leverage makes it more than actual weight. Same on the back, do the math. Trucks (don't know about vans) have less margin to carry the extra weight up front than out the back (engine is already there), so you have to have a sharp pencil doing the math.
