Actually, I think getting someone to sub as a OMB might not be too difficult - EXCEPT OF COURSE a day/night such as New Year's Eve ...
There are a few OMB I know in the area - including Zoners SteveM and Mikey - ...
BUT, it was more difficult to do it when we had the band in NYC, because - not to 'not sound humble' - I was the 'music director' and front man for the group ... We had a number of set 'routines' that we did which were difficult if not impossible for someone 'just sitting in' for a night ...
Fortunately, there were not too many times I could not make a gig ...

t.
PS Gary, hope you are 100% real soon ...
t.