If the dog crate is the size that most are, I don’t think this setup will be big enough for two bunnies. The MINIMUM floorspace for two is 4×4 feet, which I am sure the dog crate can’t satisfy, as upper levels don’t count as part of the initial floor space.
If I were you, I would just set the dog crate on the floor, and attach the xpen to either side of the door so they have lots of space. Or you could use the xpen alone.

I really think that the xpen attached on the floor to the dog crate is so much better. Floor space is more important as levels don’t count, and for two rabbits you need that floor space.
Is there a reason why you can’t just attach the 8 panels of the xpen to the dog crate door on the floor?

Hi Flint, I built a condo for my Lola a few month ago, and by your description I believe I know what you are trying to explain. I also figured using the metal fence pieces as shelves was very logical as they would fit in the crate. In my case though, I used the side walls of her first cage instead,but I really understand your plan. I used the panels originally in the corners so that I could ziptie to side of the square and have it be study enough. But after a while realized too get the most space out of it I should use an L shape, which actually made it much sturdier, if the crate is like most out, it has two doors, the one to the side is pretty useless for cleaning, so I decided that side could be zip tied with the panels. If your going to add levels,the panels will most likely work fine,but I had to use a plier to break off some of the panels, so that the level wasn’t so wide horizontally that it invaded her space below,it also cats a shadow on the bottom, and I had to put a tiny light by the cage.Is the the kind of “condo” you mean?