Have read the nine pages of forum posts at NuWa on this issue and for in my case since I just found it and not much movement. 1/8" So will go with a flex sealant and see what happens. It seems the factory sez don't worry about it but seal it to keep water out.
Thanks for guiding me in the right direction to the NuWa forum. My old login and password even still worked on the site.
Just ordered new slide seals and new decals for both sides from Kansas RV (NuWa). Gonna fix it up and use it or might trade. 09 348 SB DA 5er. Last spring got a new rear bumper from them. Thay have all the parts for old Hitch Hiker units and are great looking up want you may need to order.