I would connect with local investor agents that invest themselves and see if they have a team that cold-call and can bring you off-market deals. 

I don't send email newsletters, cold call or door knocking.

You might as well tell us that people buying property in Alaska should be subsidized because of the cold. subsidies are coercive.

Several reasons: market rates, cost of operations, risks of the tenant in particular, rental history, turnover potential, loss of rent during turnover period, "hot" or "cold" market, etc.

Maybe I'm cold blooded but I don't let the tenant's problems become my problems.

Do you do cold calling or do you just send the direct mail and wait for a call from the seller?

Like you said, It's very easy to get a Pre-Approval from a HML, however, many will get cold feet if the deal is not good. 

You could do direct to seller marketing (cold calling, texting, mailers etc.) and or connect with some of the great agents in the area that are investor friendly who already have deal flow for off market deals.

I started/continued cultivating about half dozen different commercial brokers, by taking incoming cold/warm calls from brokers for off market offers(calls I used to just hang up on) from their fund buyers and deep pocket private investors, and soon realized(as few of the brokers had warned) that off market deals for this asset are always gonna be low ball, no matter how premium my location.

I have never cold called or found off market deals so wholesale will be a challenge for me but lets connect if you can offer advice on the topic.