Hi dave239,
To see what the torque at each joint would be under worst case scenario, you should only take into account each individual joint (considering the rest as rigid links) - essentially you are left with two “sticks” connected to each other by a pivot, supported at the ends. You would need to re-do the calculation for each joint separately (one side supported by X legs and the other supported by X/2 or other fraction). This assumes that the body is symmetric (would yours have 5 legs on either side?). Your first issue will be what type of actuators to select. The approach for designing a 10 legged, 200kg robot is definitely unique - you may want to take a slightly different approach and select an actuator technology and then determine the load they can support. I can only image high power linear actuators, pneumatics or hydraulics would work. Would you also look to make each leg 3DOF? A 2DOF leg may prove far less expensive and give similar results. Do you have a sketch you can scan or something to give an idea as to what it would look like?