When is the Victoria show?
this year it was july 10 & 11th and afaik they usually host it on the second weekend in july (sat & sun).
so....imo, the cruise to the museum in coombs would have to be on the friday so it doesnt conflict with the victoria show festivities.
like i said above...great excuse to take an extra day off work and make a long weekend out of it!

...Coombs is quite the tourist trap but if you've never seen the goats on the roof 
those goats have been up there forever!! last time i was there (a few years ago) there was a pretty beat down little carnival park with some rickety rides too...the shape of the ferris wheel made the wooden roller coaster at the pne look brand new.

fun little town tho!