Would the potential rental income count towards offsetting the mortgage?  

If you are wholesaling in a market where it looks like a checkerboard and clearly builders are picking off lots, one-by-one, and you are able to source a lot at 1/5 or 2/3 approx of the retail value (the amount builders will pay) then maybe you can wholesale it without having to close on it first. 

Plus as you grow you have all your old data and you have the systems in place from the start.The only way I'd suggest using no property management software and just using excel or whatever to track rent income is if you just had a few single family homes or something as a hobby.

Don't forget to document the condition in which the home is being presented to the incoming tenants.

A huge reason why I decided to travel was so that I could make more income allowing me to invest in real estate.

If you are new to this type of investing, I suggest you pick up a copy of Lend to Live: Earn Hassle-Free Passive Income in Real Estate with Private Money Lending published by BiggerPockets.

It's total income for the year minus ALL expenses and hold backs.Of course you want to make sure you make enough in occupied months to cover vacant months.  

College students/people with job Mon-Friday in city/ people limited income rent a room.

With our income combined we can afford the homes in our area and further out, however separated we can't. 

When I started 15 years ago I was all over the map, but soon realized that I don't like low income neighborhoods and the issues that come with it, I traded out of C areas into B neighborhoods.