As long as I do the 1031 properly (intermediary and all) and don't touch the sale proceeds, nothing changes from the interest tracing perspective? 

I believe everyone expects rates to drop a bit but still will not touch those levels.

I can put you in touch with him! 

I would think I could just start using a normal checking/savings account and no longer touch the credit available in the HELOC (and hence not have to pay interest on monthly expenses).

For scaling, you likely do not want to touch your current loan.  

Are there any strategies or books that touch on this?  

I will be keeping in touch with all real estate investors to gain all perspectives. 

Touching base with a RE attorney might be a good idea to make sure there isn't anything specific locally that you don't want to violate. 

Hi Carlo,As mentioned DSCR loans vary widely based off of numerous factors, credit, LTV, Prepay type, DSCR Ratio, just to name a few.However, I am seeing rates as low as 6.625% now on DSCR products in a perfect scenario.In scenarios with low credit scores, high LTV's and short prepays we can easily be in the 9's.When looking for a DSCR loan to fit your needs, I recommend getting in touch with someone who knows what they are doing to pencil the loan in your best interest.Glad to connect and get into more detail!

They are higher touch and based in CA, which would be a benefit to you.