Be quite careful in how you arrange your business.

Under a lease-option with the terms mentioned, you will have an installment purchase contract, you will need to foreclose you cannot just evict.Any option arrangement that requires performance of any kind by the optionee (buyer) is not a true option, it is an installment sale!  

It sounds like you are familiar with these caretaker arrangements, you must have done this before? 

Yes, they are currently with one of the trustees and my mortgage broker will arrange for an RRSP swap.

You don't know what the future will hold.One thing: your property management fee assumption of 3% is very low, unless you have some kind of special arrangement (and you assume that arrangement remains true for 30 years).

That being said people like you and me who have a few properties will likely not benefit from these types of arrangements. 

I'm sure there have been plenty of cases of fallings-out or breakups that made this kind of living arrangements messy, but if you have them all on one lease, that's not your problem.

Send me a PM and we can arrange something.

You could arrange any split you both agree to. 

What you can do here is have an agreed upon arrangement with a 2nd party to act as your go-to in the case of an emergent repair that you can't address - your dad may be a good fit for this.