Install a longer ceiling molding in one piece or splice?

[octomore]

I have a room where the long side is about 4m, and I have a wooden crown molding that is just over 4m in length. This means it's possible to miter the ends of the molding and mount 4m in a single piece, but is it practical to do so in terms of handling? Definitely need a friend to help if that's the case, but even then I think it could be very tricky not to bump into the walls in the room that are already wallpapered. Is it better to splice the molding somewhere in the middle to make the job easier?

Then I wonder about splicing crown molding, should you do it like with baseboards - by mitering with a slight angle so the splice isn't a straight cut where the two pieces meet lengthwise?

 

[JohanLun]

Both probably work, I have been careless with the list without being bothered by the result.

I would miter two small pieces, get everything to fit and staple them in place, measure between them and copy the result to the long list.