If you have the built in rod holder in the gunnel, I'd take a broom handle and hang some of those offshore lure carries from it. Portable so it's not tempting anyone when your not around. By the way WELCOME
There is a unit that can be install into a gunnel if you have the depth.
There is a latched door that opens & inside holds 4/5 Plano storage boxes.
It that doesn't work, then look into Tackle Direct. I bought 2 of the Gloomis tackle boxes & they fit right under the gunnels. They are discontinued, but maybe tackle direct still has a few laying around