How bad does it look without the trim around the edge, its just that getting the trim to stick on so that it looks neat is hard to do as you have some tight corners, if you use a conntact glue it will not allow you to position the trim, if you use super-glue it makes plastic turn white, The problem is you have internal and external corners so you can not pull the trim tight and just super-glue the joint. I think it will look better with no trim, as in my opinon that black plastic/rubber finnisher is very 1980"s looking.
I did work in a body shop for 20 years and i do understand your problem.

V-tec