Brian, I did this, albeit with a 18' canoe and no penthouse, but still an EB van. It is tricky, and maybe a little more so since your canoes are shorter. If you have fairly high bars, though, with the lift the PH itself will give them, it will probably work. The trick is having another guy, or strong helper to help you get them there and off without hitting the van. I was able to just get my canoe over both ends, but had to carefully arrange my floaties, or whatever they are called. I mean those thick foam things that pop on to the canoe sides and rest on your roof.
I also had to get pretty creative with tie-downs. Since our old boat is so long, we always tied from the ends down to the bumpers but no go on the van, I had to just do straps over the boat to my bars.
I'll try to find a pic. I took one, but my situation was somewhat different so it might not help as much as some experimentation with a helper.