Sounds like an excellent fix. I'm an Alemite (Zerk) fitting person myself and your advice is well taken. I don't have HappyJac legs but Reico-Titan and the principle is the same. I will be adding grease fittings this season.
I think I would have drilled through the bottom of the landing pad to let any water out and make removal easier down the road if necessary. You can close that drilled hole with a plug button easily.
One thing that most campers never check is the tightness of the bolts that attach the legs to the plates and especially the plates to the camper. There is a lot of stress on those parts both vertically and sideways when you load and unload.