Nice job. I still think there exists a nightmare scenario for this spread. For example: if front month future at 9.5 [around the all-time spot VIX low], 2-month future stays at maybe 12.5, and VVIX is low enough, then you may have the short put at $7-7.5 and the long put potentially just $4 or $4.50.
Maybe an even higher contango is possible if some political events lined up correctly [like a major fiscal event known to happen in May]. Still, the risk/reward definitely is pretty good.