you could split a usb cable so the data lines are coming from the pi to picade, but the power feed comes from a separate power supply. would just involve some soldering, and joining of the respective cables
if you used a decent multicharger, like an Anker USB Charger, the problem would be solved as these output up to 2.8a to each output.
you could even run the 8" screen off of one of the outer outputs
mike