You are asking for opinions, here's mine. You already mucked up the looks of your bike by "bobbering" it.
Adding those rope lights makes it even look worse.
Leo
I say cut them about 4" long and mount them near the bottom of that same tube more towards the dropouts. They'd be low and tight which would hardly be noticeable until lit. I might be using this idea for my front lights. I can't find a way to mount bullet lights up front and still look clean, even that brat bike's front lights look like crap in my opinion and they probably wouldn't pass inspection here in MA anyway.
Are these rope lights duel usage, Tail/Brake???