Investment Info:Small multi-family (2-4 units) buy & hold investment.

I would look at buying 5 properties using loans that have some sort of value add aspect in a market that I believe will appreciate at the minimum of the historic national average.This may be a rather boring and unflashy answer but I believe it would be the best money spent in my current knowledge and expertise.  

We will see.Good news....they haven't asked us for any more money....yet. 

I live in FL, 2024 my first year in RE, I have a scorp private money lender/partner and other RE related businesses STR and interior design.

I would try not to tie up any of the principal in down payments.Personally, I had a family member do this same thing, but they used an investment portfolio as the collateral instead of real estate.If you play your cards right, this might be the only short-term money you ever need.Please let us know what you end up doing.

I could take on a job that pays a lot better, however, my current job gives me a lot of spare time that I can pour into real estate investing (at least 30 hours a week, potentially more at times).

Without this workout, the down payment requirements, current levels of interest rates and cost of the transaction would not be incentivizing enough to for investment. 

Sounds like this is a private money lender or a hard money lender.If you are getting funds from another source and relying on that to close, you should not put in the purchase agreement that you are buying with cash.

And would it be worthwhile investing to rent? 

Plus, that is the cheapest that money will ever be for you.  2.65% interest rate?