You could mix up some of the hamburger for sloppy joes & use the rest
for burgers on the grill. Only would have to have a heat source for the
sauce to keep it warm, but available.

I wouldn't think the sloppy joes would be a good picnic food, but if that's
what they want, let them serve themselves.

p.s. I like my hotdogs very well done myself. Yum.