Crane Support Legs Concept + Testing - Space Engineers 

I think you could try the outrigger style of the first but add a 3rd pair at the mid-point and a pair at the front, but with the hinge setup at the end... I think it will add more stability especially on uneven ground.

That was really interesting, Thank you!

Very interesting video, how did you build the suspension for that rover?

Im not a fan of the first design, its to basic. the folding out rigger is your most realistic when we talk about actual boom trucks. The third is the most creative and a few event controllers would clean up its actions real nice. In the real world a truck like this either has (4) out riggers of equal length long enough to prevent tipping giving its working weight limits. Or for example a Knuckle boom truck with a rear mounted boom has its longest/largest out riggers in the rear (as it works off of and around the rear or center mass of the truck and smaller/shorter riggs for the front. So in my opinion either take your third des and make them extend to a larger foot print. Or take the second des and use that for the rear, with third des on the front to keep it interesting.

sry if this is a stupid question but why not use landing gears on the pistons instead of blast door blocks? edit: nvm you explained it just after i wrote this xD

did you check the box to share inertia? disable it sometimes work