I can only assume people have done this, but when rolling the arches with trims on, what have people done with the trims? Since these attach to the underside of the arch lip, do people just roll the arch and the trim will follow or is the plastic trimmed from the part of the arch that's rolled? Pictures would be good if anyone has any

I cut them to match, leaving the rivet holes at the bottom, then they're just bonded on with Tigerseal or something similar.

Remove the trims first, youll need to remove the sealer from behind the lip or they wont roll properly, roll the lip then cut the trims to suit and use any rivet holes you have left and bond the rest back on, again tiger seal is usually best but once there on your not getting them off again with tiger seal

Same as alex, but I used the somthing similar option

Yep, so did I, but I can't remember what it was!