Location for a gas station is vital, you're only making money on the convenience store.

From google imagery the property next door has a large portion fenced with nothing on it (overgrown).

(Def:  a portion of the rent is credited to the tenant/buyer towards price of house when they buy.)What one should do is Lease and Option to Buy (two separate documents). 

With all the work being contained with the interior of the home, what would be a realistic estimate to contract the remaining portion of the project based on sq footage?

Ok looking at it again I’m guessing the 38k was your portion of purchase price with the rest financed.  

@Wojciech GrajewskiI agree with Nathan above but in regards to utilities you can charge each party a portion of the gas and electricity utilizing the square footage of each person’s living space.

If you do not do so in the stated timeline, you might only have a very small portion of your claim covered.

Is there another creative solution to funding the rebab portion of this REO deal using money we already have in 401k, traditional and Roth IRA?

A lot of people when they talk about house hacking say you should make your offer such that your portion of PITI plus expenses is less than what you would pay to rent a similar unit.

If those fall outside of what is reasonable or required by law than that portion or your whole lease could be seen as invalid.