He offered to advertise on the internet, interview applicants, provide me with the top three candidates so I can vet and approve.

But the seller isn't familiar with how to do it.Is the anywhere I can find a sales contract to use to buy this mobile home thorugh owner financing, that is legal in Montana.Can I pay for the forms I need on Rocket lawyer, or find for free on the internet?

Sometimes I don’t want to hear from them no matter what: your house is beautiful, the fireplace doesn’t work, can we get an early check in, we loved our stay, the house was struck by lightning and the Internet is down, great location etc. whatever it is.

Like @Alecia Loveless said you can find leases on BP and all over the internet but I would suggest that you find yourself a great lawyer that specializes in landlord tenant law and work with them on your legal documents (yes, a lease is a legal document). 

The biggest benefit as an agent of the MLS in regard to buying your own properties is that you can see the agent notes, you can receive updates through 'showing time' and you can use the official Realtor forms (Offer to purchase and contract 2-T) that make an offer look better than non-agents who write their offers on less familiar forms they find on the internet.

I'd ask them, not random people on the internet. 

You could do that through the internet but it's much easier for you because you'll put boots on the ground.

Not sure if you will find someone to help you write a lease but you can find many leases here and on the internet. 

If you want I have a decent excel deal analyzer based off of some I've found on the internet previously.

From there, search each one on the internet...