If you need four control axes, I think using 2P controls on PC emulator and stick+accelerometer on hardware is worth exploring. It may not be a good fit for a twin-stick shooter though.
One warning - last I checked, reading accelerometer inputs activates an emulated mode that makes other inputs on the Android emulator difficult to use, so you may want to make that a configurable option.
Is there a supported way to feature detect an actual accelerometer to distinguish it from emulation? Based on How can I access the name of my program? - #8 by mmoskal, maybe along the lines of control.getConfigValue(DAL.CFG_ACCELEROMETER_TYPE, 0) ?