Not sure about stovebolts, but some early vehicles had spring steel bumpers that had to be compressed at the ends to be attached to the frame brackets. A fixture about twice the width of the vehicle with jackscrews would be used to hold the bumper into a curved configuration while it was bolted to the frame brackets.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!