It seems like there are so many limitations to buying real estate with self-directed IRAs. 

SUBSTANTIALLY.I highly recommend tapping into your equity and accumulating some more assets at these prices, you will thank yourself in 3 years.The best and most cost effective way to do so is a simple cash out refinance, I don't think you should touch your primary, but leverage your investments for sure.

It’s harder to BRRRR in the Tulsa area now due interest rates, you definitely have to buy at a great discount in order to be all in low enough toget all of your money out and the rents have to be high enough to still cash flow after all expenses (PITI, Mgmt, Vac’s, Rep/Maint, CapEx, HOAs, Util).Based on being “all in” $120K in order to BRRRR and still cash flow at least $300 mo:$120K cash out amount - at 7%/30 yr ($150K+ ARV)PI = $800 mo + Taxes $150 + Ins $150 = $1100mo PITIRENT would have to be at least $2000 mo- $1100 PITI- $200 mgmt (even if self mng, it’s exp for time)- $200 vacancies- $200 Rep/Maint & CapEx= $300 mo cash flow.

Is there any way to get a construction loan for a self build WITHOUT extensive building experience and references? 

if you have proper team you can self manage. are you local to the area?

Self-education and finding a mentor or partner to learn from are much better options.

It is quite effective. 

I'm looking at purchasing a small multi-family rental property in the Allentown or Philadelphia area, and I plan to use the BRRRR strategy.I'm struggling with the best way to analyze potential properties to ensure a solid ARV and would love any advice on effective tools or methods you use.

Who are the most respected and price effective structural engineers that work your target neighborhood? 

I'm not in Boston, but I post the asking rent and do not haggle.I've got a property manager to do my screening now, but when I self-managed I used SmartMove by TransUnion.