Optimal Debt Model - Variables that impact rate

In constructing a capital stack I have gained a new appreciation for the variables that lenders consider to peg a rate. Specifically, I am focused on the SBA 7a. I plan to build a model that will help determine the optimal deal considering a few variables within control such as debt/equity, personal contributions ("skin in the game"), PG(s), timing, and a few others. Before putting this together, has anyone built something similar to get the best rate?

Desired outcome: Get the best rate while maximizing stakeholder value. Strong preference for a fixed rate.

Unknowns: Thresholds that trigger a higher or lower bank rate.

Assumed variables to consider:
1) Debt to Equity ratio (within control to an extent with the right investors)
2) Principal's personal equity contributions (within control)
3) Personal Guarantee (Possibly PG's from larger investors / within control to an extent)
4) Target collateral or other sources of collateral (Company assets not within control)
5) Sellers contributions (Sellers Note / could be within control)
6) Timing (speed to complete / within control)
7) Experience (within control / can supplement with team)
8) Company valuation (largely assumed to not be within control)
9) What else?