I see you reposted here so I copied reply here too.
After jacking the trailer up behind the rear wheel on the frame and removing the wheels, I would start with the drum and bearings. Remove the hubcap to expose the nut and cotter pin. Pull the pin and unscrew the nut. Pull the drum off and take it into the garage for cleanup, new seals and grease, maybe even bearings. With the backing plate now exposed, inspect the brakes, and magnet. I doubt your shoes will need replaced but it is possible. Buy a few cans of break cleaner and clean the backing plate, spindle, brakes, etc.
Remove the shocks. Long 3/4-inch wrench for leverage. You will have to bend the upper mounting bracket to get them off but it will bend back without damage. New shocks are about 20-30 each. Gabriel 610816. Not fun. Take break and watch ball game.
With the drum now on your workbench and plenty of rags on hand, remove the bearings and grease seal. Order a new seals from Inland or local parts store. I used National #442109 but other brands make them too. Take one with you!
Clean all of the old grease out of the cavity. Inspect the bearings and repack the grease. Parts stores have cheap bearing packers ($10) that work pretty good but you can do it by hand. Messy. I don't pack the cavity full of grease as this might hold in heat but make sure the bearings and race are coated with lots of grease. Install inner bearing. Put a light coat of grease around the new seal and then install it. I used a block of hard wood to help it seat evenly. Tap LIGHTLY with a hammer until it is flush. If it goes in crooked or bends, buy a new one and start over, as you don't want grease passing the seal and getting on your brake shoes. Reinstall drum, outer bearing, nut and new cotter pin. Don't over tighten the nut. It should have a tiny bit of axial play. Fill the hubcap with grease and tap it back on.
Then I scrapped off the crud and rust under the wheel well and used rubberized undercoating from parts store. A coat of paint on the drums won't hurt.
New radials and a spin balance is all that is left. Others please fill in the gaps I left.
Click on "New Shocks" from this link to see the picture.