That thing can only give you an extra 100W of assist power, such a waste of money, time and effort. It's really taking it to the extreme, and is meant for cheating in races, or fooling your Lycra buddies/adversaries.
The ultimate stealth ebike is any rear hub motor, hidden behind rear rack pannier bags, with the controller and battery inside the rear bags. You could very easily get away with a MXUS/QS 3kw or 5kw hub motor camouflaged black on black on black on black.
But, if you wanted to spend more money then the store bought ebikes are stealthy enough as I'd bet the majority of people really wouldnt have a clue a Levo is an ebike. But to save money, even a smaller mid drive like a BBSHD (vs larger Cyclone 3-4kw) would suffice, if you are wanting stealth, then black on black is the only way to go, water bottle batteries are an option, shark batteries would do too. Depends on what the atmosphere is like in the community that you ride in, like how NYC was cracking down on delivery ebikes, I would do rear hub/pannier and just do a lot of fake pedaling.
