Another minor suggestion- $100M cap with $5M opening bids is the same exact thing as an $80M cap with $1M opening bids- people just have to account for an extra $4M of deadweight for each empty slot, and are hence more likely to mess something up and make an illegal bid.
Really, I don't care what the cap is, I just think it would be a lot simpler to have $1M opening bids since $5M isn't adding any value to the game.