I have 30 years in the bicycle industry and believe I have seen most the jury rigged contraptions out there. For fishing rods I like the pvc zip tied to the top tube rather than the handlebars. If I had a dime for every calamity story I have heard from something added to a pair of handlebars I could afford a couple new rods and a NuCanoe to carry them around.

So with a tube at roughly 3 1/2 feet to accommodate a 7' rod your tube would slop over a bit if you tied it to the top tube but even though it looks a bit "off" it doesn't really get in the way. I have seen son creative fishing rod holders made to attache to the Delta racks like this one; https://deltacycle.com/racks-and-bag...post-bike-rack . You have to get used to a tail wagging around behind you but it is easy to tie a pvc tube to the beam on the bottom of this and bungee a small gear bag on top to hold your vest and hip boots/ waders or whatnot.

I would be interested to see what you decide you like best and decide to go with. Lots of creative people on this board so wouldn't surprise me if someone has fabricated a tubular titanium 45 degree super duper multi rod holder at some point. Best of Luck.

Bikebum