I'm currently in the works to make my Sun Sport AX into a semi limited e'bent. I have a very bad knee, two surgeries so far with a replacement within the next 5 years, just trying to put it off as long as possible.

I live in Colorado, so many of our 'hills' are more like foothill mountains. I'm talking 5-7% grades for 7-10 miles. My knee does not like that at all.

I want to do 95% of the work, using PAS (pedal assist) when needed for the long steeps and when the knee says 'no way' and I'm 10 miles from home. I have a nice Honda Helix if I want to ride around that way.

I'm looking at using a motor on the front wheel, for weight balance, with the battery either near the middle or on the rack on the rear.

My motor, I think, will be the Xiongda 2 Speed (high and low) with great high torgue for the hills.
New Invention 2-speed Ebike Motor Amazing Torque, View rear wheel brushless electric bicycle motor, Product Details from Suzhou Xiongda Motor Co., Ltd. on Alibaba.com

It's about $350 shipped from China, can use a 36v battery (it's top wattage output is 300w, it's a torgue motor, not a speed motor) and those a much less expensive and lighter weight than a 48v 1000w motor. Does not come in a wheel, so you will need to find the right rim (number of spoke holes that match the motor spoke holes) and spokes for the build. This motor can also be fitted to the rear and can handle up to a 7 speed cassette.

Lots of good into on the Endless Sphere forum. Some really amazing peple that can give you all the info you would need for your application.
Good folks.
Hope that helped,

Ginny
2011 Sun EZ Sport AX