I have tried both, I think it depends on the market you are targeting and the type of leads.

While your exact cost will depend on your market, I have a GC client in Columbus OH that is building triplexes at just under $200/SF.

AND, your son will be at the mercy of the SELLER and dependent on the SELLER's good choices for the life of the loan.

Depending on what the potential jobs offer in terms of income, does this seem like a realistic strategy?

Prosper and Lending Club also offer peer 2 peer loans, usually up to $40-$50k depending on which company you look at.

Damage to the garage, depending on how much and what it is, charge them and get it fixed. 

I invest in Boise, ID and do quite a few BRRRRs, LTRs and STRs- varying degrees of success depending on how much equity we can force and the type of back end financing we can find, but the tax benefits are great and it's a rapidly growing market and Idaho is probably the most landlord friendly state in the nation. 

Again that's just my advice, there isn't a right or a wrong answer, it depends on your future goals. 

It’s mentally tasking, which is my biggest battle now.

If an investor has the time, knowledge, capital and experience to be an active property investor then there are a number of strategies , that, depending on the economic market can be used to accelerate wealth building.