The last place you want to be is waking up at night worried about making a heloc payment.  

All of the lenders I work with on a normal basis tell me I need to have 2 years of commission pay to qualify for owner occupied loans. 

I ask because I found a house that's selling for 100k less than tax assessed value (MLS, normal house, great condition) and am wondering if I'm most likely walking into a sweet equity deal, or if there's some more nuance y'all have fun into.

I get to know them personally and get their phone numbers.. the buck stops with them normally.. in states out east or north east I am not sure I would risk much to do my own deals.. those areas are much more complicated than the CA OR WA ID NV stuff  

However, I asked for a rent roll and found that the tenant was only paying 50% of the normal rent due to the pandemic.

That's the amount of depreciation deduction you take every year.Unless you really have a superdupey perfoming rental, you should normally, at best, be in the break even ball park. 

If economy is normal, we can expect housing market to have a little over 2% appreciate per year just to beat 2% inflation. 

In a seller's market, using rehab loans can be more challenging, but in a normal or even a buyer's market, they are much easier. 

Now if you wait till life is more back to normal it might be a valid play.

If you are more comfortable with a lease that you created (b/c you know it's a good one) that shouldn't be a problem, but a MTM would be sufficient with a note that you are waiving your normal lease requirements due to their long history of good tenancy etc.