A quick and easy job. I doubt if there are any needed tools that you don't already carry with you. You may however need something to push the old bearing out. I use a large socket that is the same size as the race needed to remove the old race and set the new. This may be the only tool you need to purchase.
After you have done it once it can even be done on the side of a road in less than 50 minutes.
I used to have a popup tent trailer with 8 inch tires
. I documented my miles and every 7K miles I would change the bearings. I owned that trailer for 31 years and towed it almost 200K miles, so I changed the bearings frequently and many times. At 70 mph those little wheels were really spinning. I would not leave home on a vacation without having 2 extra sets of bearings (already prepacked with grease at home). Prepacking your spare bearings will save you about 20 minutes when you make your pit stop. I still carry a spare set of bearings I have prepacked with grease for my Snoozy.
I wouldn't pay $150.00 for a job not much more difficult than changing spark plugs on your tug.
Be prepared as a wheel seized to your spindle is a huge problem you will not be able to do on the side of the road and will result in you reaching deep into your pockets.