I actually broke a handle on my 05 Diplomat. I was able to epoxy the components back together and add a metal rod to it and worked for as long as I owned. You can still work the mechanism to get it open. The reason I repaired mine was the cost of a new one. When mine broke, Trimarck wanted something like $225.00 for the handle and it would need to be painted.
Here is something I started to do....I had a couple of doors that still lifted upward. I learned to grab the bottom of the door and lift up, rather than put all the stress on the handle itself.
If you can't get the mechanism to work, you can spin open the black tank drain cover and reach up into the bay and possibly open it.