Not a Stimulator, but for a better float in fast water, I tie a version of regular old Elk Wing Caddis (EWC) but I use either sheet craft foam or narrow cylindrical foam for the body.
With the sheet foam, I choose my color, cut it in a narrow strip and wind it on for a segmented body. With the cylindrical foam, I use 1/8" cylinders, split it lengthwise 2/3 of the way though with a razor blade, slide it over the hook shank and make a few lashing wraps fore & aft.
Or, I use the 3/32" cylinders and wrap it around the hook shank for a segmented body which only works for small flies because the cylinders aren’t that long.
Other than the body, the rest is a regular EWC. Extra wraps of hackle help with buoyancy too.
The secret with using foam for a slim body is not to wrap it too tightly or compress it too much with thread. Doing either kills some of the natural buoyancy of closed cell EVA foam. In addition, don’t use light sizes of thread, they can cut right through foam.
For the most part, the “Foamies” (as I call them) float like a cork and are super easy to tie.
