I don't know about aftermarket boots for ball joints, but try NAPA and Auto Zone to see what they have. The best thing to do for now is over grease the joint until grease is totally filled the cup as it is the water and grime from the outside that will accelerate wear. If it can't get in, then no contamination, just normal friction wear. The lower needs grease quickly already. If you can't find cover boots, Looks like the ball joints press into the knuckle, so you'll need specialized equipment for that and if this is coil springs and not leaf, then have a shop do it. Coil springs can be difficult to control with simple jacks. Maybe you have air springs, anyway if the spring is pushing on either the upper or lower arm there is a lot of force to support the front of the coach. Air should be easiest in that you can dump all the pressure and control the force that way. All this assumes that you will need to replace the boots, and you can take the knuckle off and take to a shop to install new ball joints. You would need to get toe set, so might as well check caster and camber too.