That looks like a cool walker. From your drawing I gather that your femur is 5cm center to center? So I'll assume your tars is also 5 and apply a worst case scenario: Bot supported on 3 nearly outstretched legs. Then you'd have something like 2.5/9 = .27kg of support per leg. You could support about 810g. From the parts you listed you're already at 476g. If you can keep your structure less than 300g it would probably be ok.
Also you could try this:
leg load.png [ 10.52 KiB | Viewed 424 times ]
The red line represents the force on the leg. If you keep the distances, represented by the purple and yellow lines, as equal as possible in your gait sequence then you can keep the loads on your hip and knee servos close to equal and support more load.