I'm trying to piece together a roof rack that'll use one of the factory crossbars on my '05 Dodge minivan to secure the rear of my Rocky Mounts wheel trays (fronts will be mounted to a Thule load bar I have on hand). Yakima's online tool just tells me I can't do this (it's no good at thinking outside the box and mkaing do with what's on hand). Is there some source that would tell me profile of the various Yakima horizontal Mighty Mounts so I'll know what fits the 2.5"x.75" cross section of my factory rack? Yeah, I know I could just use the universal mighty mounts, and I will as a last resort, but I was hoping to find a specific MM that fit. Surely among the dozen or so that they make, one has the matching profile?

And lest anyone tell me "just spend the bucks to do it right," I've already got a fine hitch rack for primary transport. This is just for those occasions when I need capacity for a couple more bikes. TIA,
- Joe