I learned how to do this job on drum brake equipped VW Beetles, circa 1972 or so, when we had that lousy yellow fibrous grease. The stuff we have today is so much better. If you need to change bearings and races, there are are few other tricks...
1) bolt the hub/drum or hub/disc rotor to the wheel, that makes it easier to knock out the old races and install the new ones, because its not moving around...
2) before installing new races leave them in the freezer for while, it makes it easier to tap them in, and using a bearing driver, makes it easier still and prevents any damage to the new races...
3) when adjusting the new bearings, I tighten the spindle nut to about 20 ft lbs while rotating the wheel, then take the big socket off the extension and use it to loosen the spindle nut a bit, then just tighten the nut by hand (snug) with the socket, and install the cotter pin or locking tab whichever one you have. There should be next to no play when rocking the wheel...
Its surprising that they put a 6,000 lb axle on that trailer with no brakes...were there any originally, or were they never installed? Here in NY that boat would be over the limit for needing brakes legally (3,000 lbs).
I had a new axle made years back with the Tie Down style Super Lube hubs and they are great. They are very easy to maintain and being able to flush out all the grease each season makes the bearings last a very long time. In fact I installed this in 2004 and have the same bearings in it since then. I changed the seals once (only because I had the drums off doing brake maintenance) and that's it.
As far as brakes I go against the grain sticking with drum brakes. With a few minor mods and using better quality parts (galvax coated drums, o-ring seal wheel cylinders, galvanized packing plates) and some regular maintenance (every other season remove drum, put a bit of grease on pivot points, adjust shoes) they work very well, do not drag like disc brakes do and do not need a troublesome back up solenoid like disc brakes. Drums can be designed to be free backing.
I took standard aluminum wheel cylinders and made them less prone to seizing by packing the piston with brake grease and sealing the dust boot to the cylinder with high temp RTV. This prevents the seizing of the piston due to corrosion which also happens with disc brakes, at least in salt water.
BTW, for those of you used to electric brakes, I found (on trailerpartsdepot.com) a company that makes galvanized electric trailer brakes. In freshwater I bet they would work great, with better control than surge brake and far cheaper than electric over hydraulic brakes. Here in the salt I prefer to sick with surge, but in fresh water I'd give them a try....
http://www.trailerpartsdepot.com/p-422- ... galvx.aspxhttp://www.trailerpartsdepot.com/p-419- ... vx-7k.aspx