Trying to push in some new polybushes (Bearmach) into my rear trailing arms (were rubber bushes before) and they just don't want to go.
Currently I'm using a length of M12 threaded rod, some washers and M12 nuts to push them in. This method worked fine on when I did the radius arms.

Looking at the rear trailing arm bush houses, they could do with a bit of a clean up.
Is it worth trying to find a 30mm wire wheel to clean up the inside of the housings (Did something similar on the radius arms) or just using a vice and swinging off it like a chimp until the bush goes home.

Try getting a flap wheel or similar, if you leave the inside rough then it could wear the new bush prematurely. Something like this

I use a vice to push my bushes in. Wind it tight and if it doesn't go in tap the top of the arm with an hammer and it goes bit by bit. Never had an issue with any bushes until I did my panhard rod bushes they were a bitch to get in