You could bring less down and possibly have a lower interest rate since you will be living there.

If the loan amount you are looking for is small relative to the value of the first and the second property combined, they are very well secured on a LTV%; ask for a 1% point lower rate.If you don't want to Cross Collateralize, do you have any CD's or MM you can transfer to this bank as collateral. 

We do know the border had its issues, but currently illegal crossing are lower compared to when Trump left in office.

The price points do make it hard to cash flow even with the lower interest rate subject tos. 

If your rental rate is below the market anyway, a Tenant might consider this to be win as they would get the lower rate in the beginning and just rise to the level they were looking at everywhere else.Step clauses can be written right into the lease, or created by using 3 month lease terms with an auto-renewal at the step up rental rate price. 

Some PMC's will charge a lower percentage fee, but will charge it whether tenant paying or not.

In my experience, the local banks are going to get you better rates and lower fees with their commercial loan products than the "DSCR lenders".

Happy to chat...being a local GC takes out a lot of the risk of the biggest variable for most investors (unpredictable rehab costs) and also allows you to consider more options than the average investor, with your rehab costs being significantly lower.

All else being equal, lower mortgage rates reduce the cost of ownership and, thereby, allow more people to afford to buy.

I would look at the DSCR loan as the first option.By the way, I suspect you are going to be disappointed by any refi appraisals   ADUs typically appraise poorly   JADUs can lower the property value Vs having the space as part of the primary unit.