Attaching parts on the ground.

[Vodostar]

So I have a mission to fix a rover on minmus. It needs wheels. When I attach a wheel it sticks into the ground and then the whole rover goes shooting into the sky spinning uncontrollably (in spite of SAS being on). Maybe it lands right side up... maybe upside down... maybe a fuel tank explodes. Maybe the engineer can push it back upright. Maybe pushing it just sends it off spinning into the sky again.

Is there a way to avoid this problem? Or is this just repeat from a save point 100 times till I'm lucky enough to have a usable rover at the end of the process?

[Vodostar]

OK so I took landing legs off the lander and used them as jacks. That was a PITA, but it worked.

But now I have no electric power. I have fuel. I have fuel cells. Why don't I have power? Is this fixable?

[magnemoe]

If the rover has an driver seat or an command module an kerbal can enter and turn it on, else you need an battery or an solar panel to give it enough power to start the fuel cell from the rover. 
This require that the rover has an probe core , not all have that so you need to add that too. 
Just tested kerbals can not turn fuel cells on from the outside. 

Hint for adding wheels. Attach an reaction wheel to the rover. This let you flip it upside down and you can add wheels and then flip back. Turn the reaction wheel off then driving but it can be handy again if rover flips over while driving.
 

Edited February 11, 2022 by magnemoe

[miklkit]

Hinges.  I stick hinges on them and turn them up, then attach wheels to the hinges.   Turn the hinges down and drive away.  And gotta turn fuel cells on.