Pete, have you looked at the Thule T2 Classic? This is what I use for our bikes (with adapter for 4 bikes) and have loved it since day one.
It can handle bikes up to 60 pounds each and has very wide tracks for whatever size tires you have. The tire attachments also adjust, allowing you to set whatever wheelbase you need. The 2" hitch bar actually is attached to the hitch receiver tube by a threaded bolt, which must be tightened with a wrench, so it has zero play in it. The rear tires are attached to the rack with a rubberized strap and the front wheels are locked in with a bar that drops down and locks over them.
The only way I can see it not working for you is if you have front fenders on your bikes. This would prevent the front bar from holding the bikes in place.
Hope this helps.