Mike has the right idea - more bolts, at greater spacing.
In a '97 model, are the bolts anchored in wood? Somewhere we had several long threads about reinforcing the stirrup mounting by installing either heavier aluminum tubing along the lower edge of the shell, or installing a steel strap inside or above the existing tubing. Larry Loo had some good thoughts.
I think this was one of them.
http://www.trailmanorowners.com/foru...read.php?t=537
Bill