I dont have an actual recipe...but here is my thought...I used to do this in college for breakfast bars...
Get any kind of nut, raisins, peanut butter, etc obviously anything you can find/want with hi protien content...add some Fiber 1 in for texture and substance and follow the directions for rice krispie treats or s'mores on the back of the golden grahms box...that should give you something to hold it all together with...
like I said just a thought. The marshmello might be too hi in sugar...but I'll see if I can find anything else.