if you are getting 'sway' from a 5x10 utility trailer, then either the trailer design is crap or you are not loading it correctly...
With that light of a load (under #500 tongue weight), you don't need a WD setup at all and even if you did put one on, it won't really be doing much WD..
Put your heavy stuff up front and the lighter stuff in the back and it should tow straight as an arrow..
If not, then the trailer design is wrong, meaning the trailer axle is not back far enough on the trailer to tow properly...
Good luck!
Mitch