Let me start off by saying that is the stupidest idea ever. Maybe he can get away with crap like that where he is from, but it DEF wouldn't fly down here. Save him a lot of heartache and squash that awful idea. Regardless of what i say, its pretty safe to say your friend probably wont do it anyways. Its fun to talk about buying jet packs, but until you actually own them, they are 100% legal and in your name, its just a dream... and probably a stupid one at that. Id be willing to bet its not as simple as "hooking the thing" up to some piece of shit 2 stroke Sea Do XP and VIOALA your hovering like iron man
Hypothetically speaking, if this terrible culmination of ideas comes to light, when someone gets killed or paralyzed and there is no insurance to cover the 350k in medical bills or physical damage to private/public property. Your buddy will most likely face jail time and a ton of fines, which is exactly what he'd deserve. My policy covers up to ONE MILLION DOLLARS and its not cheap by any stretch of the imagination. Regardless of whatever moronic statement like "rent at your own risk" that wont hold bearing in court and his ass will be grass. Not in 1000000 years. If owning a rental were as easy as that, everyone would be doing it. There are laws, regulations, rules, and business standards almost anywhere you go.
Please understand, Im not mad at you, so please dont take my sarcastic attitude or my smart ass response as a personal attack on you, or as me being some 'keyboard warrior' by ANY means. I would say this to anyones face without hesitation. I pay thousands and thousands of dollars just to be able to insure one jet ski every quarter, and i have a fleet of them. Hearing about someone who isnt remotely serious about getting into a rental business kinda irritates me. It would with anyone that has put the blood sweat and tears into something like this. That being said, its a free world. Good luck and dive safe