Will the long rim mechs be added at any point? or will that be put off for now as that information is part of the $2 backer package on kickstarter?
You can download the 'compcon-ks-content.zip' file from the app page, extract it somewhere, then open COMP/CON > OPTIONS in the top nav bar > Import content package and select the extracted folder.
After that, you'll get a little toggle to turn on the long rim mechs
It's a little convoluted, and they're missing art, but there's an incoming rework to better accommodate expansion packages