Is there anyway to bolt a rod or something on the opposite side of the handle?
You might get enough pull like that.
Or maybe even try to heat the latch and bend it back towards the door and you could get some extra travel that way as well.
There is a way to add that but the lever can't move enough to unlatch the door. It's about 1/4 inch from the roll bar and it needs about a inch of swing to unlatch the door