oh that diagonal...! that would definitely work ... I have not been able to predict up or down spikes > 55% on a portfolio level so I tend to stay away from spreads that incur big debits. That "reverse" diagonal you have incurs a big debit vs. OTM put calendars which are "teenies"....
Yeah, it is a big debit. I added contracts on the short side to reduce the debit and delta. Sold 1.3 fronts for each back.