musselman brings up a good point. On some trailer the side rail IS part of the trailer support. Before you do any cutting on the side rail, question the manufacturer on this. With my trailer, this was not the case. Last winter I added a side gate and everything has been fine.
A1 Lawn@Landscapes, rather then build a podium to raise your leaf loader, you might check with the manufacturer to see if they offer an extension to get the needed height. I have the Lesco model and they offered a 4ft extension for $125, so I took that route. The only problem concerning height with mine is the vacuum hose itself. The vacuum hose has to take a sharp incline to go over the top of the side rail of the trailer. I can either raise the loader itself, cut out a section of the rail or live with it until I remount the loader to the front of the truck. I have chosen the last option.
Good luck
MATT