Good Morning Angela, I am a Realtor in Florida and I understand this completely. ( I am not one of those agents) Thank goodness, I would suggest not letting them know what you intend on doing as they only see $$$ signs, and if you are looking for something off-market then their commission will be less,  I suggest looking for the deals yourself through Zillow, Make me move is a for sale by owner, your county records, for pre-foreclosures,  do your research first, then contact an agent to gain access to a property you may want. 

Has anyone successfully gained approval from a lender in effort to avoid due on sale?

@Sean DawsonIf your thinking about doing it in Columbus it might be difficult given the market conditions..I think in most cases besides eating capital gains seller would prefer a lump sum of cash at closing..Sellers would consider a take back note if they have difficulty selling the property, hiding a deficiency or need to unload it quick..

And after you gave the apartments back to your uncle for free- he will have effectively stolen two apartments from you.You've made a 50% gain on your condos.

Or an owner carry offer with an installment sale, so they don’t receive all of their gains in one year.

As an investor, I want to find the property where the seller has outdated rents, so I can find the value add gains. 

So here is one of the last trades I did (stopped trading to focus on setting up RE business):One of my best trades actually. 37% gain in less than 1 hr.

As Jay pointed out the real money is in the equity gain that you can eventually crystalize.  

How could I go about gaining enough trust from someone for them to allow me to put their home under contract.

If not, consider something where you can get your feet wet and gain some experience.