Pull out bumper rack for bikes

[Smitty]

I have a Cougar Fifth Wheel 327RES with the pull out bumper rack. It has a rod that you can secure upright with a large cotter pin. This rod looks like it would be used for securing your bicycles to it. I currently use a bolt on bike rack which has hoops that you put the tires into and also has the upright pole that you then secure the bikes to. What I cannot figure out is how you would securely hold your bikes on the pull out rack since the bottom looks like ribbed plastic and the upright rod just doesn't seem like it would hold the bikes alone. Anyone use the rack for bikes? If so can you give me some pointers or modifications that would work for two bikes. Thanks