I have just been attending the curtains in my Exec, and I agree with you they are not easy to remove and install, but I had to do it twice
At the end of last summer I took them down and gave them wash, then struggled like blazes to rehang them, got them back up and realised I had them on the wrong sides(they all looked alike!!) So last week when I was bored, and looking for something to do, I decided to sort them out.
Anyway the front rails just unclip and drop down making it easy to undo the stopping screw, the curtains then just slides off. The side ones I had to undo the middle screw holding the rail to the frame by gently easing the end of the rail downwards (rather than trying to screw it) then gently eased the rail in a downward angle allowing you a better angle for access to the start of the rail for the very miniscule hangers.
For a cheap and easy way to close off the Cab from the habitation area , I bought a Shower rail and curtain(180 x 180) from Wilkinsons, and cut the rail to length, fixed two cup hooks on the bulkhead and clipped it on. This can be removed very easily when not required.