I've set up an 'embedded' version of Gentoo Linux that boots into E-UAE in about 15s. The Linux part of the installation takes only about 16MB on the hard drive. It's far more optimised than KXLight, but you need to do a bit of work to customise it for your hardware.
Any hardware supported by Linux should be available to the emulation - wireless networking, USB, etc.
I'm working on a How-To, but if you want the gory details, I'd be glad to email a WIP version to you!