Your platform definitely has a lot more motor torque than mine, from the sounds of it. In which case, I should think it would have plenty of torque with just 2 wheels on the ground to get over any moderate-sized humps. You just might need to step up the drive level.
Such a platform definitely needs a lot sensors to prevent crashing into things. Eg, bumpers and IR proximity detectors. You might also use an accelerometer module to tell when it's starting to tilt. If the sensors say it's tilted and it's not run into something, then maybe you need to step up the drive to get over a hump. Good sensing of the environment is the #1 key to robotics.