Something that you might want to check out is this kickstarter: https://www.kickstarter.com/projects/shiftsmarttrainer/shift...

Its a device that you set on the Peloton that does the automatic resistance changes to match the hills in Zwift by using a motor to turn the big red knob. Basically it converts your Peloton into a smart trainer that you can use with Zwift without having to mod your Peloton at all.

Note: I am not affiliated with the project but I have backed it.