100% want to use an attorney to draft your docs.That being said, before you draft docs you need to figure out what the GP/LP structure is (equity/splits/fees).

Also, there's a process which will cost money to put a mobile home on top of the lot including movings costs, hook ups, set-up fees, etc. 

In 2023 it brought in around $8700 TO ME (after PM fees (20%), taxes, and everything are taken out) when this places costs me $40K per year between mortgage and HOA fees and all the other incidentals that come with being an owner.

What other factors should I consider?

You may use the following factors to help you focus on certain target markets:Economic Stability: Seek out regions where the economy is expanding or steady.

Although they might vary, investment property loans typically need a down payment of 15% to 25% or more.BRRRR method: If you are thinking of using the BRRRR (Buy, Rehab, Rent, Refinance, Repeat) method, you will want sufficient funds for the initial purchase, the renovations, and the holding fees until the property is refinanced and rented out.

It’s up to investors to do their numbers and budget for vacancy and operating costs because this will, again, vary depending on the market, size of the home, and plenty of other factors. 

I started the process of a portfolio loan with Corevest and ALMOST closed with them, but due to me being a foreign (non-US) national, they were demanding a lot of things like cashflow management (all rent goes to them first, I had to ask for draws to pay for repairs), they wanted monthly reporting, and they wanted me ask my property managers to sign away their right to be paid management fee first (basically Corevest wanted to be paid before everyone else).

How does one figure out what is a fair fee to pay architects? 

Approval will be based on income potential of property, your credit score, appraisal, down payment, the DSCR ratio - there are quite a few factors that play into the approval.