With a C152 there isn’t room to mount the RAM yoke mount to the shaft of the yoke without restricting elevator down travel, but you can (just) mount it round the squishy base of the yoke itself. But it’s rather in the way - I prefer to mount it on the P2 side.
With a PA28 though it’s fine - I always check for control restriction but it can be done. The weight isn’t significant (though that may be what he meant).