As @Bradley Buxton mentioned, you can make many markets work! 

I once ran across a hot tub where the customer mentioned it tingled when they were getting in it .

Because to provide the seller with value the wholesaler MUST possess the experience and knowledge mentioned above, otherwise the wholesaler is merely tying up the sellers property under false pretenses.  

If so you may have some full doc options which have the best rates typically and terms.Like others have mentioned you have DSCR loans too but this only allows you to purchase non owner occupied properties (not primary residence or second home occupancy type properties).

As others mentioned, not a big deal for the solo 401k itself to lend.

And you'll have the best rate/points options with a primary residence.Option #2 is great, especially if you're willing to move into one of the units (because the down payment minimum is just 5% or 3.5% depending on program), but as you mentioned it's really tough here to find small multifamily here.

But the programs you mentioned are designed for what you are after.

You mentioned buying a fixer upper with your HELOC and now are talking about a 20% down payment.

As mentioned have an attorney or title company draft the note and mortgage.

I would go with a combo W/D unit just like @Greg M. mentioned above.