We all invest in real estate in order to make money, and keep in mind that someone who can only afford to live in a mobile home and seller-finance to buy the land is probably tight on funds. 

For the son to qualify for the $250k exclusion, I believe he would most likely need to meet the ownership and use test, meaning he needs to own and live in the home as his primary residence for at least two of the last five years before the sale.

Working horrible job, living horrible, no golden streets of opportunity found.

It is not very difficult or complicated to evaluate commercial real estate, there are plenty of good books available that can teach you how, textbooks, online courses, community college classes, even excellent youtube videos etc, and it is actually quite enjoyable in the process to learn.

If your able to move and live in the unit do that.  

I live here in Albuquerque and have been investing here for the past 15 years.

Especially if you built something to rent or live in. 

My wife and I use to live in central GA and in North Carolina but moved out to Arizona a couple years ago.

(For context, it's a 2700 sf 4 bd 3 bath house in an upscale Northern California suburb.)Kitchen A: Traditional, features a 48 in fridge, 36 in cooktop, window sink (no view), pantry.Kitchen B: Designer, features a 60 in fridge, 48 in range, large kitchen window (no view), sink facing living/dining room; unfortunately no pantryKitchen C: A Little Bit of Both, features a 48 in fridge, 48 in range, sink facing living/dining room, pantry, unfortunately there's no window.Total countertop space is roughly the same (22 ft)  in all three layouts.

Your primary residence - if you've lived in it for 2 out of the 5 years prior to selling you'll get the $250K/$500K tax free iike @Clint Galliano said.