It sounds like you've done everything you could!
I have FREQUENTLY been in this situation- in the current economic climate producers have a had JOB trying to get shows up-- AEA allows for us not to have understudies & swings-- and we have to punt!
I do think it's important that your producing staff acknowledge the challenges in this show and come up with solutions for the next time you do a show like this! Try to have a post-mortem with your producer and make sure you have a list of challenges the company has faced due to no swings, adding a performance without checking the availability of the cast etc....
Wishing you a smoother run!