Thank you for taking the time to reply.
I got the time this evening to do some additional testing.
Using my July 29th save game, I visited the faulty lot with a sim from another family and then got the house to load in Live mode for the original family by clicking on the front door and switching control.
I tested it again with a later save game and got the same results. Then I created a new save with the original family at their home lot and exited the game. I restarted the game and was able to load the new save without crashing.
It might be time for my sim family to move to a more modest home, but it looks like I have at least a temporary solution.