I have used both conventional greased and oil bath ... each has advantages and disadvantages.
Oil bath hubs like these ...
(Amazon linky) do seem to run cooler and for longer between services, however, it is necessary to check the oil level
often. Thankfully most are easy to check. Drivers of big rigs are required by law to check them at a minimum at the beginning and end of each shift. If the oil leaks out they will more than likely self destruct in less than a day's driving because the oil will drain entirely where the grease will tend to stay in a greased hub (to a point).
The conventional greased hub is actually my preference. A quick look at the back seal for leaks before each trip and the occasional temperature check is adequate for these. My hubs, properly lubed will last for 20k even 30k miles between services or two years when I clean and repack just to check for issues if nothing else. Most grease formulations will break down with age just as much as with mileage so personally I error on the side of caution.
I'm not a fan of bearing buddies. The whole idea is for boat trailers where water contaminated grease would be forced out by the bearing buddy after each "dunking." This requires carrying a grease gun and will make a tremendous mess (back of rim/tires/fenders) if overdone. Because of the mess, most people quit greasing them each time and they end up being the same as an expensive conventional cap. Even a boat trailer with daily "dunkings" will be fine for several weeks, even a couple of months without the buddies (re-pack 'em before storing!).
One more item ... there is a quality issue here as well. Highly polished top of the line precision bearings are expensive. They run smoother, cooler, break down lubricants slower, and require less maintenance in the long run. These bearings do not come from the factory in a HF trailer. The bearings on the lower side of the spectrum are OK for the conditions that most teardrops experience, but will require more attention than the top of the line. When you re-pack, watch for discolorations of the metal or
ANY rough or pitted spots. Roll the parts together with your fingers without lubrication and feel for any roughness or uneven spots. These are warnings of impending problems. In these cases I would suggest replacing bearings
and races with a good if not high quality bearing.