Are your tires 'C' rated or are they D's?
If they are C's, keep the cold pressure at the max. If D's you have some leeway.
As for greasing, do you have the rubber caps and the grease zerks on the axle stub ends? If so, you could just give them a couple of squirts before every trip. If you are going on a long trip, I would psuh grease into them, slowly, until a fair bit of old grease came out. Then clean off the excess, and you should be good to go.