While I’ve considered cash-out refinancing or HELOCs, the high rates make these options less appealing.I’m debating between using cash to acquire more SFRs or diversifying into mixed-use retail properties.

I understand why carriers associate Condo/PUD construction with greater liability risk (I am sure being based in Philadelphia, a jury friendly city doesn't help either) but curious which carriers others are finding to price coverage without this exclusion and also price the coverage competitively.This also serves as a reminder to review the coverage when you hire a GC for more substantial or unique construction assignments. 

Have you and your wife considered exploring fully turnkey properties as an option?

The land banker, the long term landlord, the neighbor that wants to expand their home, or the horse owning owner occupant with no other options?  

There's zero reason to do this when there are plenty of options to avoid it. 

I have lenders that can fund in just a few days and are willing to finance up to 90% of the purchase price and up to 100% of the rehab budget, even for first time investors.

Financing options do exist: hard money loans, renovation loans, and some traditional mortgages can be used on distressed properties if criteria are met.

You've demonstrated success on your current duplex, so friends/family may be excitted to join in on the next.Congrats on the success so far,-Steve

HELOCs are definitely a good option for financing BRRRRs.

That said, I'm grateful for the alternatives you present--you're keeping the bottom line in mind, so I appreciate your help in exploring options that achieve the bottom line for the investors.