If you are talking about the kind of form that is just a board with uprights on the end for the tips to sit on and a block for the riser and clamps mid limb to hold the deflex down then I am sure it will not work with good results. The type of form I am picturing has voids between the riser/midlimb/tips and probably weighs ten pounds or so. It has to be solid contact all the way down on a level and smooth flowing serface or you will have a disaster. It has to be at least clamped or banded every 2-3 inches or so with a backing strip for even pressure. The most popular method is to use a fire hose between top and bottom sectional forms. Any shortcuts here and you will definately have a failure. I could be picturing a different type of form than you are thinking though.