How do you plan to fold the wings without a center section? How would disconnecting the split wing pivot bearing be simpler than the standard flea wing fold.If you wanted to stick with just two-axis then a split wing gives that with a single control system. Plus, it gives an easy way to fold the wing just by unhooking the outer struts since the wing is already in two halves.
Why would making the front wing fixed and putting elevons on the rear wing be better?Rear wing ailerons only make sense if you make them elevons and have the fore wing be fixed.
The idea behind the Piojo is a simple 3 axis flea. I think the best way to approach that is to just make a standard 2 axis flea and give it ailerons. The simplest and safest way to do that is to put them on the rear wing.