ITS A 10 FT BOX!!!! any loader can drop the load center of it........FROM THE REAR DUH!!!!!!!!!!!!!!!!!!!
you realize the OP stated a dump insert, which is an insert that goes in the existing bed of an 8' pickup truck.... Also there are no trucks on the road 10' wide without oversize load permits. You also might want to know there are very few loader buckets smaller then 6' wide unless we are talking garden tractors, So as someone stated before most trucks are loaded from the sides unless it is something palletized. Sorry none of this is really relevant to the thread starters question, it just irks me when smartasses try and make a a dik out of someone when they dont know much about what they are talking about
To answer the threadstarters question I would give the customer the option of vinyl on the tailgate and if they insist on a flat panel I would weld some clips on for mounting or even make a thin alum pan
sign with a removable subframe and screw or weld the subframe to the back. that would be the nicest look and concealed fasteners, If they are just going to be super cheap then just sell them a .080 or even .125 alum panel and tek screw it right to the ribs of the gate