[BigLew]

John123,

IMHO, I would invstigate a pair/2pair of new hubs w/drum brakes. Their are certainly less expensive (about $350 at W/M prices) in terms of both time AND money than repair/replace what you have plus new SS discs with new hubs- a fair comparison. As you said, it's the 400 mile trip that most concerns you and new hubs and brakes answers both your braking ability and hub concerns. Yes, it's more $$ than repaired/rebuilt bearings/hubs, but when you start the long trip there is the confidence factor even when the A/holes swerve and cut you off or you get into a stop and go stretch of the trip- likely.
If the trailer is otherwise sound and the axles are good, then new hubs & brakes are easy enough to install in an afternoon once you have the parts purchased.

Then, when you get to you destination, pull the brakes off. Personally I agree you probably don't need to subject them to a dunking twice/season for a 1/4 miles worth of driving, and you will have essentially new brakes to re-install on well maintained hubs when it comes time for resale. Heck, you could pull the hubs off for the winter as well and keep them inside where they will not wear as much and it will be a show stopper for the would be thieves you might worry about through the winter months.

It could all be a deal maker rather than a deal breaker at resale!

Just my 2 cents.

Good luck. Congrats and enjoy. Take care and be well.