Hmmm, by coincidence I just experienced this as I rewrapped my vintage Opus III this morning with a thick synthetic leather tape. No way the thick tape would tuck in with the tight expanding bar end plugs. So I wrapped the tape even with the end of the bars. Then I used the same brown finishing tape I used up top. I ran a thin overlap on the bar tape with most of it sticking out past the bar. I then tucked this tape into the bar and inserted the bar plugs. I've actually used this technique on other bars to add a touch of contrasting color to the bike. Many would probably shudder at someone doing such a thing, LOL!
This is the same method used on my Prologue, best picture I have to show what I'm talking about.
