When will your cars typically get home and how long will the longest to charge take? At 80 amps, 5 hours. Will both cars typically be home for 5 hours each? If so, and you have two HPWCs, then schedule one to start 5 hours before it leaves, and the other for 5 hours before that. That way you've left the most time possible and won't have any overlap. (To be on the safe side, you could schedule them 6 hours apart, in case one comes home late.) But let's face it, you won't really need to do that since you're not going to be charging from empty every time. But also, you could use charge limiting on the cars, mixed with scheduling, to further protect yourself from overlap if it's an issue.
But the HPWC + 40-amp outlet folks recommend sounds good.
Then there's my plan: I hope we replace my other half's SUV with a Tesla, one day, if it lasts that long. With two Teslas . . . well, we keep quite different hours (and always have--no matter what schedule we're on, they're never direct overlaps). So I'll move the cable from one to the other. "Every night," I hear you all gasp? Yes--not a big deal, what, it takes seconds to do this. So if you decide on one HPWC but want the faster charging, you could plug in whoever-leaves-earliest first, then before going to bed, swap cables. You don't mention commute times, but maybe this could work.