Add more options for what players may do on claimed chunks. For example...
chests contents: 0 = no interaction, 1 = view, 2 = add, 3 = remove
other item inventories: 0 = no interaction, 1 = view, 2 = add, 3 = remove
Minecarts/boats that the chunk owner placed: 0 = no interaction, 1= Mount/dismount, 2 = move
operate redstone components like switches, levers, buttons, tripwires, etc: true, false
Open/close doors: true, false
PvP: true, false
place projectiles into item inventories(to prevent using dispensers for PvP damage): true, false
place tnt blocks: true, false
place tnt into item inventories(to prevent using dispensers for griefing): true, false
Also allow ops to set global defaults for what protections are active for newly claimed chunks. Unprivileged users should then be given the option to set their own personal defaults for all future claims. Furthermore, permissions should be editable on individual chunks after claiming, or optionally update all claimed chunks. Ops should be able to set which permissions are editable by unprivileged users, so certain permissions are always set to the global default.