I had a wheel bearing go on me once and i went through the "that wont happen to me again" thing so i started pumping loads of grease in every now and again, i ended up just blowing the seals at the back of the wheel

so then i got the bearing savers and found they were quite good as it keeps the grease in contact with the bearings and i also now take the trailer up to my local garage and get him to check the bearings once a year so hopfully it should be ok now.
I have also had the loose nuts thing, driving up loch lomondside once the trailer wheel came off

all the nuts had came off, god knows how that happened but now i check them all the time, it might be worthwhile getting some of those things you see on lorry whel nuts , they are wee green arrows that show you that the nuts are all still tightened they clip over the nuts and should all be lined up if the nuts are all tight.