If I buy a lot in park and boy friend has one too. can we stay in one 6 month and the next 6 in the other. not same name, different owners.

Only use one key card for 6 months. .then use other.

Different names on the ownership, you should be fine.

Same situation years back and we were not allowed, no.

I have friends coming in, for how long can they rent the guest spot?

No you can't

He can be your 30 day guest or you can be his 30 day guest...

Usually no