Though, if there's not I'm not sure how that would work out in the long run. 

In my experience, an amicable mutual termination of a lease can often work out in the landlord's favor. 

That'll take the guess work out of it when you receive applications and make decisions like this so much easier because applicants will either meet your criteria or they won't.

I'll let you know if the current lot I'm focused on doesn't work out.

From you POV, is it ethical to work with multiple agents at the same time or it's better to select one and "fire" them if it doesn't work out after a certain amount of weeks/months?

told them we can work out a plan where they pay % now so that they don't have to pay so much back later.  

Do you schedule workout/self-development time?

In this market, you need to get creative if you want things to work out fruitfully for you.

How would you work out structure repairs and maintenance (roof)?

If the house truly has income potential, possibly you could work out a private money loan deal with family/friends/investor to loan you the additional down payment to get the bigger house for the income potential.If your DTI supports a higher purchase price than your initial pre-approval then talk to the mortgage broker.The last thought that comes to mind is if you find a home that already has a leased tenant that would help demonstrate that the house is already an income property and cash flowing so the bank may see this as a lower risk of default.Ultimately the lender is looking to minimize risk so putting you in more house than you can afford isn't going to happen without some other risk mitigation steps like the ones I noted.