I use the Arvika (www.arvika.ca
) 2" receiver mounted on the front A-frame with Thule DoubleTrack carrier. A lot smoother ride for the bikes in the middle of the setup than they get whipping around on the back bumper. You would have to remove the bike rack before opening the slide, but if the slide is the same height as our bunk (pretty sure it is as both clear the dinette and J-Steel) then the Arvika can stay mounted; although it does come off quite easily as well.
Sure it's more expensive than making your own, but it is also quick to install. And since you see the bikes at all times, you won't be wondering if they are still hanging on back there.