However, my property manager is having the hardest time finding a qualified tenant.

Hey I'm located just under an hour south of Sac but I currently have a few listings in the area, full disclosure I'm not a lender, but from what I understand you could still qualify for 3-4 units even with Interest rates at high 6's - low 7's.

So in our previous example: $500k purchase, $225k assumable mortgage..the lender might allow the qualified buyer to take over the $225k put $100k down in cash and obtain a second loan for $175k from another lender.

First thing is to go to your Bank and get Qualified for a Loan.

Sadly you would need to either have a spouse qualify for REPS (you cannot due to w2) or either make under 100k per year so you can deduct up to 25k of losses per year and actively participate(this is different then material participation). 

I would be cautious about using "national averages" as a way to try to qualify or disqualify someone. 

Quote from @Gabriel Ortega: looking at 75-80% ltv for a heloc, yes all rental income are in schedule e  Hey Gabriel, If you are only a W2 earner the bank statement program will not work out, since you must be self-employed to qualify.

It's highly recommended to seek personalized advice from a qualified CPA, EA, or tax professional who can assess your specific situation based on the facts presented

She did not qualify for a mortgage loan to build on her own so he became a coborrower which meant he had to be on the title. 

Leaving your W2 job can affect your ability to qualify for a HELOC.