"All the axle weight is never over the hole."

Yep, that's kinda the point, isn't it? A wheeled machine will always have the axle sitting in the hole it is pressing and there's the problem.

Again, I suggest looking at the soils where you're planning to use the tractor. Some are susceptible to compaction and some aren't. Some grow better when compacted and some don't. If what you are doing is working for you, I'd suggest you continue. If what I'm doing or what you're doing will work for rollig - who knows? He asked for ideas and suggestions. Now he has a few and the rest is up to him for him to decide.