I repack and readjust thrust in bearings on my heavy duty trailer every spring. It gets tons of use -sever use-every season-1000's of tons. Be sure to use a good quality old fashion Li grease-the super sticky stuff-I have had a horrible experiences with synthetics so they have lost my vote in this application....forever! I would also replace the 32 year old bearings and dont forget the races and grease seals. Also remember to hand pack the bearing cartridges when they are brand new-very important! Removing the races and seals should not be a big deal on a utility trailer-hammer and bronze punch/hardwood block works good...not the same at all on a truck chassy trailer....where the drive axle is used as the axle-these are lubed with gear oil and the bearing/seal configuration is different. Tearing the hub and spindle down will allow you to inspect the condition of the equipment- remember rust and iron oxide scale is harder than the spindle material-it is a great abrasive and can cause a lot of wear and lead to failure and more corrosion-water and dirt is the enemy....  A good auto parts store with be of great assistant in in these process-along with a mic and a person that knows how to use it-the spindle must be measured too. I have my own take on the bearing buddy grease covers-I believe if you maintain the trailer properly there is real no need for them...and they do have the tendency to blow the inwale grease seal out if one is over zealous with the grease gun.  I have also found it very useful and important to have a redundant ground on the the trailer-super easy to do when you rewire it-Good luck. And for GOD's sake dont forget to put the receiver pin in! ;)