Vaughn, If your exposures are into the "minutes" end of things... you'd be fine with not having it in a shutter. I tend to shoot with exposure times of 1/2 second to 2 or 3 seconds and, hence, my wanting it in a shutter.
I don't often use filters so I can't suggest any way of mounting one on a barrel lens. But, I'm sure some of the other guys here on the forum may have an idea and wade in with recommendations.
The Wollie 159 is one I've been looking for but I've not seen one around for sale lately.
Let us know how things work out with mounting that 600mm beast!
Cheers
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