When repacking trailer wheel bearings just about any good grease will do.
However the grease I've always used for my trailer wheel bearings is the Valvoline VV986 SynPower Synthetic Wheel Bearing Grease.
That's a great grease for trailer wheel bearings and is what I've always used however if I didn't have anymore and needed some other type of grease I would use any other type of grease for the wheel bearings.
A few other good types of grease for trailer wheel bearings are Allstar Timken ALL78241 Red Wheel Bearing Grease and Timken GR224C Wheel Bearing Grease.
You should repack your trailer wheel bearings every 10,000 to 15,000 miles to ensure they are properly lubricated and free of any debris.
That way you can also check for any potential problems with the wheel bearings and fix them at home before you go on the road with it.