I would recommend against this. Check your local and EU laws -- Anything coming out of your IP address may end up being your responsibility if it turns out to be illegal.
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.