We have one of the bike racks that mounts off the front hitch and we love it. It works great for carrying 2 bikes. It is made by Top Pop and you can see their website at www.toppoprails.com. The company is out of Canada and the owner is very helpful...great guy!
You said you have a rack mounted on the rear how did you do that?I have tried a couple of different way to carry bikes on our rig. First attempt was to mount the bikes on the Trail-Air hitch, while this worked OK it had some down sides. To put the bikes on or off the rack you have to be standing on the tailgate of the truck and then move them to the ground. The other negative is the bikes create a wind resistance problem and if you put a cover on the bikes it makes this worst. You do have to purchase a new cover every year because the wind just shreds it.
Now I have a rack mounted on the rear and it so far it works well. I do have to change the mount so the license plate can be seen.
Hope this helps.
Dave
for less than $100 i had a 2" receiver hitch installed on the front of our 2008 F250. it was a bolt on affair using holes left by Ford for this purpose. For about $80 bucks I got a 2 bike carrier that slides into the 2" receiver. The bikes are below eye level while driving and ride more smoothly than what I've seen watching 5vers going down the road with rear mounts and certainly more easy to deal with than mounts on the 5ver hitch or on top of the truck. The receiver will also serve a second function when we get our kayaks. The hitch shop has a "goal post" mount that fits between the receiver and bike rack that provides support for the front of the kayaks and a removable foam bar that fits over the cab to support the back of the kayaks.
will post a picture album on my profile when the rig is complete.