Forward is just a notation. Realistically you could put it anywhere you want in whatever polarity you want. Between two wheels for a kiwi makes sense because when you're going "forward" only two wheels are powered (simplifying your trig problem).
Regardless of what you do, kiwi drives shouldn't have a problem driving forward or backward
Hope this helps.
__________________

Be Healthy. Never Stop Learning. Say It Like It Is. Own It. Like our values?
Flexware Innovation is hiring!. We're looking for Senior Automation, Software, and System Engineers.
Check us out!