just a thought but why do you need bearings on some thing that does not turn very often? the simple pipe within a pipe is a very strong and reliable joint that dirt and debris will not affect. dont reinvent the the wheel for a simple joint. drill and tap a hole on the outer pipe and insert a zerk fitting so that it can be greased and this joint will never fail. just make sure to clean the outside of the inner pipe and the inside of the outer, have a decent fit and forget about replacing bearings ever again. this will make a strong and very functional joint.
but hey thats just my two cents.
Pook