I had this idea (when shipping was cheaper) about renting heat miners during the Nth hemisphere summer. Sending it to Australia for 3-4 months during our winter.

yea, I thought about this as well. I've hard though that its just such a pain to ship the miners around that no many people do it.
I do wonder though if thats because the current miner hardware isn't really made for it, and now that we have open source hardware we could build miners that are much more rigid and made to be shipped around the world multiple times a year.