Providing that it will fit at the end of your fretboard, here's a tiny mag pickup which won't block your soundhole.
https://www.musiciansfriend.com/acce...-endpin-preamp
I'm personally unfamiliar with the ToneWood Amp and why it presents such a feedback problem, but if a mag pickup is necessary for best results, then an active mag (like the one above) shouldn't be any more feedback prone than a passive mag.
No matter what pickup you use, you won't be able to get an unlimited amount of gain from the system. There are many ways to discourage feedback (phase inverting, notching problem frequencies, preamps with automatic feedback zappers). Sometimes its enough to just turn the level down a bit and play harder.