We have also lost 2 wheel hubs - one when the trailer was only a year old. Speed not a factor in our situation, since I drive between 55-62 mph when towing. Had that first one repaired at a truck repair shop - he was able to save the axle but replaced spindle & hub. Second one, the entire axle was replaced. The guys that replaced the axle told us that the (trailer) service shop had used too much grease of the wrong kind.
Sounds like one either gets lucky (which we did with our PUP and HTT) or one has to be mechanically inclined in order to own a TT. We are not. No way do we want to get involved with doing our own hub greasing, especially after the trouble we have had. I can totally relate to the OP's statement that he's skittish about towing - so am I.
And with all the "bad advice" out there - who do you trust? Maybe we should just give up on RVing...???? Or expect to replace axles (NOT cheap) every couple years..