id bend the rails too
after looking at pics courtesy of google id try using 2 adjustabe spanners on the rear vertical part of the rails or some large jawed mole grip type pliers directly where the clamp goes
using rags to protect the paint of course
it might be possible to put one rail in the clamp and pushing the other rail in , alternating sides to keep it from going crooked . the biggest problem will be keeping its shape as it lacks a hull
borrowed this from sheldon brown
"You'll notice that I do call them "saddles," not "seats." There is a reason for this. A "seat" is something you sit on, and is designed to bear essentially your entire weight. Recumbent bicycles have "seats," but conventional upright bicycles have saddles. A saddle is intended to carry some, but not all of your weight. The rest of your weight is mainly carried by your legs, and some by your hands and arms. "
but i prefer to say seat , saddle sounds a bit crap
i do say fine sir my saddle is making my posterior rather stuporous
mate my seat is making my fooking arse numb
"It also has a seat. I don’t use it, but you probably will for the first few years until you build up the muscle."