Accepting bitcoin as payment is cool.

Giving tenants money back after their payment appreciates in USD terms over time, that is nice of you and offers an incentive for tenants to start paying in bitcoin.

I personally wouldn't do that part, as it seems like one more thing everyone has to track. If every tenant paid in fiat, but I converted it right away into bitcoin after receiving the payments, the idea I would sell any portion of that bitcoin and give USD back to tenants isn't something that would cross my mind later.

If I were to do something like this with my tenants (I have five apartments), I would probably just offer a small discount if they pay in bitcoin. I would intepret it as saving me time and fees, since I wouldn't be converting funds to bitcoin myself. But with on-chain fees the tenant would pay, this probably would be a wash for them, because the discount probably wouldn't be much. Rent here is near a grand a month too, so paying by lightning may be more difficult.

If you didn't do the 50/50 share thing, would your tenants still pay in bitcoin? I would imagine their fiat payment is cheaper for them, unless you are doing payments via a layer 2. But then your payments aren't straight to cold storage with that (which I don't personally mind - I stack a while and then do large UTXOs to cold anyways).