The lowers are pretty safe as far as chafe goes. The aft lowers are only subject to chafe from the mainsail when sailing down wind. I would wait for the fuzzy signs of chafe to start to know where to apply a cover, if it is even needed. If it never begins to fuzz, then you don't have to worry about it. I would recommend applying a soft chafe cover, such as "baggy wrinkles" to protect the sails as service or chafe sleeves will hurt the sail.
The forward lowers are only subject to chafe from a lazy sheet that rides up and down as the sail moves. To avoid this issue, I walk forward and pull out excess sheet and lay it on the deck. This way all motion in the lazy sheet is confined to the length from deck to clew, rather than from shroud to clew.
After over 1000 miles, my forward lower has slight fuzz forming, but nothing structural that should be of concern.
