I have not had the best of luck with this arrangement in the past and wonder if it would be advisable/legal to have a different income standard when qualifying unrelated prospects vs a married couple.

Provide a price adjustment to the unit that has been paying for the electric service.I have the same situation and we were able to work out a nice arrangement.

I haven't done that arrangement - but I've given it some thought.  

I understand that everything is up for negotiations but im curious what a typical arrangement is like on that example?

I am sure there are standards (which others can comment on) however at the end, you have to give him enough of what he wants and he has to give you enough what you want to get the deal done.I suggest that you write down how you want the arrangement to be laid out, then talk to him with the goal of seeing if he is interested.

Terms and conditions, such as interest rates, points, application fees, promissory notes, inspections, LTV, length of project, appraisals, etc can all factor in to what makes or breaks a funding arrangement.

People who have and keep steady jobs, have good credit scores and history, and a stable record of living arrangements are unlikely to b the type of people who will destroy your house or not pay rent.

Since you have a very loose arrangement with your tenant you could always ask them to help you out with the fees since they are late on their payment, but forcing them to seems like a crappy move. 

I suggest you arrange for two or three specific dates/times to have your "money partners" view the home.

Although we have a formal mentoring program here, wherein a mentor is assigned and you both agree to a service/compensation arrangement,  I never used it.