Build a RC controlled DC motor sets

I want to build a RC control 2 motor set which can be attached to 2 wheels a large frame such as a baby stroller/shopping cart and can carry weight of 30 kilograms and move at variable speeds of approximately 20kmph. No axle needs to be built. Have a look at the attached page and video, it shows what I want to build. [login to view URL] I will source the parts for you online once you specify what would be required to build a larger version of what is shown on the page mentioned above