Having owned several PWC's over the years, I offer this advise:
1) Replace the bearings and races, not just lube them. They are likely neglected, and frequently dunked in water, possibly salt water. Bearing kits are cheap, and saves the time you would have spent thoroughly cleaning and inspecting the old ones.
2) If It has either size tire used on 8 inch rims, consider upgrading to either of the two 12 inch tire sizes readily available at Walmarts or places like ETrailer.com. Your rims are likely somewhat rusty where the face meets the outer rim anyway. The taller tires spin slower, run cooler, and bounce less on bumps. The wheel bearings will also run cooler.
Fenders may need to be replaced or modified.
3) tongue weight may be very light, resulting in a lot of noise from the hitch slop. Consider making/buying a small storage box for the front of trailer for tools, etc.