The Sovereign would look ideal on paper in terms of cabin size and range but don't even think of putting one into a humid maritime environment - the corrosion proofing simply isn't up to it.
You are right about the 800XP, the rear divan makes the longer flights very uncomfortable for 8 pax - other than that it would be a very affordable option, just make sure you get one that has had a recent E/F&G check.
CL30 sounds ideal to me, fits all your requirements and is a fairly simple machine to maintain.
Happy shopping
McD