Windowed Envelopes

Has anyone been able to get these to print on the newer Canon printers?
We were able to print windowed envelopes on our c810 but never on the v1000.
Recently we switched to running two v900s but neither one can do the windowed envelopes without wrinking them badly. I've tried a bunch of different settings and better/worse quality of envelopes and haven't come up with a fix.

Does anyone have some magical hidden setting they know about on the printers and/or in the paper stock profiles that will solve this? We don't do a lot of them (not enough to get a dedicated envelope printer).

Are you using laser compatible window envelopes?

In Australia we can buy window faced envelopes with a glassine window to work on laser printers. The normal windows melt and wrinkle, but with glassine windows you don't have those issues. I'm sure there are options worldwide for these.