In reading the description of the frame in QuiltnNan's link it appears that the original poles extended to king size(120") or without the extension, could be used for crib size. Did your seller replace with poles that do not adjust? By the way, 10 feet may not be long enough for a king-size quilt. I had one once that was 117 inches. On my 12' table I barely had room to work with the machine(changing bobbin, etc).
Anyway, can't you use your frame as it is for a crib size quilt? I have a 12' table and do this all the time. You mount the quilt lined up with the middle of your leaders as you do with any quilt. The only problem would be if your side clamps can't reach that far from the sides but maybe you could somehow make them longer? My table has velcro straps and clamps. The straps are very long and I can adjust for any length I need.
Hope you work our your problem.