Between rates being higher and terms being shorter Helocs can also have issues when it comes to DTI and not having reserves. 

You should have no problem finding an oceanfront property that covers your mortgage/taxes even with rising taxes.

In this high-interest rate/high-price market, house-hacking is more about offsetting as much cost as you can.

I am currently renting at 40% below market rate rent and will be putting 5% down.

You can get higher but the rates will be higher as well and it will be a lender that doesn't sell the loan to Fannie. 

Especially with higher interest rates and also location dependent might be more geared toword appreciation. 

The fix and flip loan will either more expensive, a higher rate, or generally a bridge loan without rehab (it may also require more down) in most cases. 

How has the occupancy rate been for you and Avg nightly rates? 

I've never done a dscr loan but if rates drop after your (most likely) pre-payment penalty ends, I'd refi.

Be extremely conservative - assume very low rent growth, very low appreciation, and fairly stagnant interest rates, meaning minimal opportunity to increase cash flow through a refinance.