In terms of your grandfather living there as long as he's not the owner having a dwelling fire/rental property insurance policy is appropriate.As @Greg Scott pointed out he should have a renters insurance policy whether or not he's actually paying rent.In terms of liability coverage, that depends on what you have to protect so there's no one-size fits all approach.

Especially with a long-term hold approach.

Just curious if the numbers look right to experienced wholesalers before I lock it in...Let's assume the property is in a healthy market area and that my ARV is correct...

It's crucial that we find a balanced approach.

If it's not healthy, then it's probably not a good rental in the first place and you should probably sell it and get something that's a better rental (if you can't improve the numbers). 

Especially with a long-term hold approach.

I would approach the Village and ask for a permit to move a mobile home into the park.

I was approached by people who are interested in leasing my property long term and use it for cooperate business travel accommodation. 

Nice wishful  thinking but if you approach real estate investing thinking it's going to be a completely passive endeavor, then your chances of failure will be much greater. 

Is anyone aware of any companies that purchase remainderman interests in properties or any experience on who I should approach on selling my interest?