I just installed one on my bike. It was $400 CAD, expensive IMO but I'm using my RW4 primarily for dropping off and picking up my kids 5 days a week so I think it'll make the ride a lot more pleasant for them. My kids wear boots on rainy days so no worries about wet feet

The frame screws into the caboose ends and shares a bolt with the outermost bars. The connection point on the Conestoga is "U" shaped so you only have to unscrew the bolts about 1/2inch for placement/removal of the frame as opposed to unscrewing the bolts completely. It comes with longer bolts to replace the standard caboose ones.

I was really pleasantly surprised by the quality of construction of the cover itself. It's super nice and really well-made. I can post some pics of it if you guys are interested.