Heavy equipment should have no effect on a proper asphalt driveway. They would be harder on pavers. If you want to protect the edges from cracking with heavy equipment, just place a long 4 X 8 on the soil surface right next to the edge of the asphalt. That way, when the heavy vehicle rolls from the asphalt to the softer ground, the timber will keep the wheels from sinking in and applying pressure to the asphalt edge. In addition, if you are going to put in a pool, it usually is best to have the concrete pumped from a pumper truck for a continuous pour. If you do that, the hose or boom can reach pretty far, and you may be able to avoid having a bunch of heavy traffic running through the yard. I've had dump trucks deliver 17 ton loads of rock to my concrete driveway apron, and they had to get there by driving down my asphalt driveway. There was zero damage.

Ya, its not the asphalt or the concrete...its the base.

If you have 6-8 of stone that has been down for 10+ years I'd be real comfortable with that base, personally. Especially if it isn't washed rock, if it has fines and is solid.

IMO, your base should be larger than your top...that is you should see gravel extending out beyond the asphalt, then you landscape up to the finished drive. That way someone runs wide and a tire drops off the drive, its onto a supported spot, not just soil. Ideally, eh?