As I understand your situation:

Put the 3-Ton on the floor.
If it's unstable, put it on a board.
Put some wood block above the jack.
Lifting point is some part of the trailer frame before or aft of the tire

Be sure other side tires are blocked and tongue is held firmly in place
(maybe by having toungue attached to two vehicle) so trailer won't move.

If all of the above is still unstable, you could also lift one side
of the wheel (say in front of it) and block that up. Then remove
your jack to the rear side of the tire and lift that. Could block
that up.

Whatever you do...just be CAREFUL that the trailer
is stable.


Wheel bearings need greasing. No, not WD40. Use real grease. Some
have a fitting for a grease gun. Others do not.