I understand unused reserves is also included but much more variable and anything is icing on the cake! 

.• Planning to increase rent by around 5-8% annually.I've tried using tools like DealCheck, the BP calculator, and creating my own spreadsheets, but I'm finding it increasingly confusing to put all these variables together.

Determining whether to do a cost segregation study or not has a lot variables.

Cost is between 125 per square foot for a modular home not including utilities, foundation, GC costs and other variables.

Be aware of zoning laws and building permits for these variables could cost your investment unnecessary time and resources.

I recommend you do this each year to adjust for utility increases and other variables.

Current situation:a) Spouse and I own our residence out-right (fun pandemic bought low/sold high story).b) Low on cash at the moment, but I have a $400k heloc getting ready to close soon (variable rate, interest only, 8% currently).c) Long-term goal is to own Buy and Holds to pad our retirement and retire my spouse early.d) I quit my job last year and have time and motivation to manage properties and portfolio.

If I used the HELOC, the investment needs to generate >9%.I recognize there are many variables not listed here but would love to hear from more experienced investors on generally how you think about using cash vs. home equity to grow your portfolio in the current environment.

There's just a lot of variables to fill in.  

Too many variables go into pricing to rely on canned prices.I use Planswift for takeoffs.