Anyone uses these besides the boxter 611 one ?

I ran out of room in my rx 4 people + 1 baby. Crib + stroller + all the baby junk left me with no room in the trunk. I'm looking to get one of these and just put cloth on the room. Leaving me with room in the trunk for all the stroller and other stuff. This is basically for extended vacation.. not to use all the time. I'm looking at large size which is around 6x inches. I dont think I need 80+ inches length.

Any other things I should look at or for ?

Off their website, it seems that a few will mount on the RX but it seems like a generic description. I have that thinner flat cross bar.

Fits Thule rack systems, round bars and most factory racks

Thule