Battery Box Armrest/Jump Seat

Has anyone made an armrest/cushion that goes atop the battery box in the cab? I have a couple of spare seat frames and was thinking about narrowing the back rest section and mounting it there on top of the battery box. As an adult, seeing straight out the windshield is impossible sitting there, but maybe a place for a child to sit?

I made some canvas armrests that had a foam cushion. tried to sell them but no one was interested. I like 'em because hitting my funny bone on the steel corners isn't funny.