Motorized 80cc trike with pedals for bicycle path rules



So I want to build a tricycle with 80cc 2-stroke engine for about <200Eur and I want it to be considered as a bicycle so i can ride on paths legaly (bc as long as it has pedals ur ok). Now the easiest way of geting pedals would be to put them on the front wheel with freehub but that can get expensive i think (and hard to pedal), and I cant think of any design that would connect pedals with rear axle (which would have engine connected to it) and where pedals wouldnt spin when the engine is spinning the wheels. So can any of you guys send me some pictures or anything that would show some tricycle with that design in mind?