This tough and I look forward to hearing what others have to say - I don't have the answer for you. My father was a lone wolf in business and life - and his allergic reaction to partnerships rubbed off on me. I know I need a partner to grow - for the psychological support in running a large portfolio if nothing else.
Yet trusting someone else to essentially "marry" them financially seems like such a headache.
In your particular case let's play devil's advocate - why do you need this friend in your business? Are you talking about simply running/owning one mobile home park? If so - how lacking are your people skills?
1 - Just kinda quiet
2 - A real introvert
3 - Have some kind of extreme social anxiety and you can't even have a normal conversation with somebody without creeping them out?
The reason I ask is because if it is just #1 or #2 I would question your need for this friend to be your partner. If you have capital, can hold a conversation when you need to without it destroying you psychologically, and are good with numbers - I am not sure what your friend brings to the table that is so valuable you need him even though he has almost no capital.
This is the mobile home business - you're not selling ice to Eskimos. If you are analytical, logical, organized and good with numbers and have capital - well I think you're 90% of the way to finding buying and running a park successfully.
You don't have to be a glad handing back slapping extrovert to get brokers to show you deals - you do have to show you have capital and are a serious buyer. You don't need to have the people skills of Bill Clinton to do that.
Not trying to be negative here but real estate is full of dreamers without a dollar. They are literally a dime a dozen (no disrespect to anyone reading this who doesn't have much capital - we all started there a long time ago).
Why do you need this person so badly? Have you considered hiring a good full or part-time administrative assistant instead?