Nice details. I do have one critique for you though, this could be a side effect of how you took the screen shots but it looks like some of the mechs are terribly unbalanced, like they are falling over backwards.
I remembered I had a link to artist's blog, who was probably behind the Front Mission mech design - http://mechanic.blog25.fc2.com/ . Have fun! And keep in mind there are various styles of robots, including ugly Gundam-like robots. But you can find there cool Wanzers as well
Now that you asked about SketchyPhysics, I think you will definitely need it for adjusting poses - I mean, you could set angles or rotation of arms, legs, torso and more in fly Looking at your robots, I think you shouldn't have any problems - basically you would have to add servos, adjust their rotation angles and join them together with robot body parts.
Very cool designs on deviantart by the way - I think you should post them there