> Investors want to back us but, at this scale of capital, need conventional equity and less structural bespokeness.

This seems exactly backwards. At this scale you can establish as much "bespokeness" as you want. The investors want in and will sign pretty much anything.

It reminds me of the old joke from Paul Getty:

If you owe the bank $100 that's your problem. If you owe the bank $100 million, that's the bank's problem.