Two U-Joints

Im designing a 2Dof and one of the concerns I have about the typical u-joint based builds is to be more flexible in terms of the loads the platform can handle. Specially in designing mine to have three monitors integrated into the moving frame so I don’t want to have to play too much finding the perfect balance and rather have more like a fixed spot to place the u-joints where I can get a good compromise between platform efficiency and ease of setup.
Are there any projects out there having an additional u-joint in the front besides the one that goes below the seat?

I have built a couple of 2dof and can't understand why you would want a u joint at the front. That for one would require 2 frames. Make an issue of reinforcing the motor mounts. I'm not sure what 3 motors would do to help unless you are using 2 for sway and roll and one for pitch and surge. I once tried to make a sim using 2 u joints to build a aim on-top of in order to separate surge/sway from pitch/roll and it was a levelling nightmare. Keep it simple is my suggestion.

Thanks for your reply. The reason why is because I will have heavy stuff on the front, mainly three monitors and their aluminum mount so I thought that having an additional u-joint at the front would help the motors and the balancing of the platform during the initial setup.