John,
Re: the rig sinking into black top, ours is parked on blacktop, and you have a point, when it gets hot, things tend to sink in.
Boards have left the most "damage", or in other words, have left the deepest ruts. Tires have left "divits".
Now, granted, we live in Michigan so we have a few days that are in the 90's, a few more in the 80's, but nothing like, say, Arizona. (Maybe they don't use blacktop in Arizona??
)
But, with our temps, the tires have not sunk into the blacktop enough to present a serious problem. Even the boards have not been a serious problem. We have always been able to get them OUT of the blacktop.
The divits and board ruts have never gone away once there. We just live with them, and since the 5er is always parked in the same spot, it does not effect our parking of cars or trucks or whatever.