Another thing to consider is that most people would likely rent it for the unified memory and AI usage. Speaking from experience, your M3 Ultra will run _hot_ while performing; you'll need to plan a good, cool environment that the machine lives in, and set the fans to always run via something like MacsFanControl or some other utility, since it won't engage the fan at a higher rate just because your GPU is pegged and generating all the heat.
The third thing is knowing how to balance out its memory usage. SSDs have a finite lifetime in terms of writes. Macs are _very_ good at not wearing out SSDs, but if your renter botches something in a config and you spend days or weeks swapping in and out of virtual memory, your machine will wear faster and harder.