I'm looking at conventional loans because of the preferable amortization schedule and lower interest rates, but maybe I'm simply barking up the wrong tree. 

It has not been updated since I bought, new, in 2009 and is in average shape.If I sell, I'll make a 20% profit off the original investment (10 yrs).Would you sell or would you keep?

That is not 7% of the profit but 7% of the total amount given to the seller.

The Tiny Home would be acquired for ~$50,000, and he suggests it could generate gross profit of $4000 a month.

Unless there is a lot of profit in the deal it may or may not be worth your time since you also have to find a buyer on the back end.

@Joseph Bogorad, put simply, anytime its principal and interest expenses total higher than 50% of its rental income (in this case, 61% at the asking price), you're looking at a probable negative cash flow scenario (given that your other expenses are commonly around 50% of its income).

Because I’ve been in the non-profit world from right out of high school, I have no start up money whatsoever.

All you can do is making the best educated guess and be a good enough problem solver once you have it to turn a profit.

Several offers I had on several properties cut my potential profit by 2.

However it is still misleading and not factually correct or are you simply expressing an opinion?