> This risks pricing the common, which is bad. It certainly isn't the same as preferred, due to superior rights (liquidation preference most seriously)

The common/preferred issue is a good criticism and I have added a paragraph partially addressing it. For your convenience, here it is:

This issue deserves more thorough treatment but as a temporary remedy, I’d offer up this solution: unbundle the liquidation preferences and other preferred terms from the underlying equity. Instead of an investor purchasing preferred shares, they would purchase common shares and separately purchase rights or swaps to synthetically realize the economic exposure of the preferences. Since the investor would be purchasing the synthetics at their theoretical market value, the increase in the company’s cash would equal the increase in its liabilities. Therefore, this transaction, theoretically, would not have any effect on the dilution or value of the equity held by any of the founders, employees, or investors.