Adding stab Jack's

Hi all! I recently acquired a 2009 Flaggstaff 32' 2 slide outs, front kitchen rear bedroom, (actually closer to 35') from my Dad when he upgraded to a new Grand Design. It has 4 stab Jack's as expected. They are the long are type not the scissor style. The problem is the Jack's seem to loosen. Not settling as much as actually eeking up. I would go but them when my dad had the trailer and see them off the ground. I am planning on adding 4 scissor style Jack's and I'm looking for advice. I'm thinking forward and aft of the axles. But I could go to the far end of the frame. In the rest I could go between the bumper and the trailer body. Up front I could go farther forward than the factory installed ones also. Any advice would be appreciated. Thanks in advance.
Keith