If you've put RF pigment sticks over acrylic, the only areas that need the clear gesso to stick are the acrylic areas - if the clear gesso doesn't stick to the oily or cray pas areas, no worries since the cwm/oils WILL! Also, though I do use clear gesso over acrylic, you "can" proceed with cwm/oils over the acrylic without the extra clear gesso step IF the acrylic has tooth and is not too slick. So, you can scuff up the acrylic with sand paper; I've done this and it works ok, but I do the added clear gesso step as a precaution as there is definitely better adhesion this way.