If your wife or family members can co-sign it might work out

Does anyone use apartments.com for pre-screening (since they do a credit check) and then have applicants who pass fill out a separate application (not with all the same details, but more specific screening questions)?

Your monthly income will need to be at least twice as much as the mortgage payment will be in order to qualify, but you can get a co-signor to supplement your income as a plan B.

Question for those who have had pre-rehab appraisals done for financing a combined purchase/rehab loan.

The problem was that the appraiser used the value from the pre flip sale, but my property was much closer in condition to the property post flip.

Recently I applied for pre-approval in order to start looking for small multi-family units to do an owner occupied house hack, I was, unfortunately, denied pre-approval due to my low income.So I had an idea and I was wondering if this is 1) Legal/Feasible 2) Effective/Smart or Not.

You could either move into that side and repeat the process or hire the work out depending on your situation.  

I am happy to report, per the chart below, near term lumber futures (1 month out) have finally hit pre-covid levels and we should really start to be putting pressure on our suppliers be it HomeDepot, Lowes, BMC, or any other local supplier you source from. 

I agree with @Joseph P Finkelstein that finding a co-signer to supplement your income is your best bet, if at all possible.

This formula will help educate your clients and help you pre qualify potential prospects with nothing more than a pen, pad, and a conversation.