Another Classic owner with the same issue! I've sort of being ignoring mine - probably for too long - because I wasn't sure there was much i could do.
Is the centre section fibreglass and the end caps plastic? I never seem to have much success with epoxies or products like JB weld on plastic, but it sounds as though your repair is holding up so maybe I'll give it a try.
I wonder if the whole works could be painted after to spruce everything up an hide the repairs - I know there are specialty paints for car bumpers & such.
On a related issue, the centre section of the bumper on our trailer has been very much dulle by UV I suppose.
I ca get it looking good again with products such as Armorall and the similar products, bit it a very temporary remedy.
Brian & Connie Mitchell
2005 Classic 30'
Hensley Arrow / Centramatics
2008 GMC Sierra SLT 2500HD,4x4,Crew Cab, Diesel, Leer cap.