Top and bottom spars with vertical sheet balsa sheer webbing are stiffer and stronger for the weight. Helps with torsional rigidity, too.  Sheer webbing the TE if it's made of two pieces of 1/16" (like many) is also a fine idea.

If you're thinking of the Ringmaster type spar, that's a pretty useless expenditure of weight. I doubt that you're thinking of the I-beamer sort of spar, but as much as people like the looks of all those ribs, they're inferior in both bending and torsion, to a "D-Tube" or "C-Tube" structure.

Bottom line is that the structure depends a lot on how big the model is (Super Clown being of moderate size), and the bigger the model or longer the span &/or higher aspect ratio, the more critical the structural design. That is, if one cares about weight and performance. How much do you expect from your model vs. how much work are you willing to put into it?  Steve