Generally, if the other same sized units in the area are getting $X/month, the little things are not going to allow you to get too much more than that.

Adding extra walls or portions of walls would add to the cost of encasing them. 

Isn't there something that says that can be done, each owner of the SFR owns a portion like 1/15th and that passes onto the next owner when the property sells.I guess just sticking with the question of what does the person who owns the road get out of this if they don't own any of the property?

As long as you do that (allow them the ability to have them installed, and don't "prohibit" the modification) then you have made a reasonable accommodation and are ok as far as the ADA/fair housing goes.Obviously you really should read the appropriate portion of the act yourself, and if you have any doubts or questions seek appropriate legal counsel.

Low down payment loans will warrant a higher discount for a longer portion of the loan term regardless of payment success.  

(Or perhaps they want a better interest rate.)In return for you co-signing on the loan, they would be sharing a portion of the profits from whatever venture they are using the loan for.

About in the middle of the property is a SFR that is in need of minor updates and repairs and on the northern portion of the property are two single-wide trailers (southern portion is pasture).

If you were to go to a third party lender on this size deal, the loan would have personal guarantees so that inherent in the seller financing is the concept that to sweeten the deal, the seller is providing you an economic advantage hence the higher price.

Lucky for you, you shouldn't have to go very far because there are plenty of agents here in your area who know how to think like an investor because many of them are investors.Your agent will size you up in a sense to ensure you're a serious investor with the means to purchase, and not just an eager window shopper.

I am assuming that your lot size is about 35ft and therefore you need to allow for 7ft in the back.