It is usually fairly easy to get the trolley onto the trailer. Technique rather than brute force is sometimes enough – though the design of the trailer/trolley can effect this.
Check that any bearings run freely and are well greased. This includes any metal on metal contacts that have to move against each other. This can make a massive difference.
The technique that works for us, and I have seen used on other trailer makes:
boat on trolley, loosely secure stem to trolley
unload any gear in the boat – minimum weight helps
crew1 sits on stern to lift bow high into the air
crew2 pushes trailer under the boat and into position
crew2 checks position
crew1 lowers bow (slowly!)
Checking the position can be v important – depends on trailer design.
This should leave a few inches to pull the trolley home.
hope that helps