Have different types and levels of guardedness.
The guards in guarded towns seems to have super high competence, perhaps the North Towns will have just a small force equipped from the towns' meager resources.
They may concentrate on protecting citizens and those who help the town through trade and donations.
(Must be Liked or better to be protected, for what it's worth.)
Perhaps players could gift the unguarded towns with freed slaves (except Den) and mercs.
Maybe help the unguarded towns pay for [non-uber] militia.
Sort of like how in TC militia could be bought, but these are NORMAL NPC guards, with regular stats, equipment, etc.
They just act like normal guards, and have no allegiance to a controlling gang. They would be of the same type as NPCs found in the respective areas, with the same gear. No laser rifles, rocket launchers, etc.
(Unless such items are given as gifts. This would not give the skill to use them, though.)
Also maybe these guards will expire if the payment account is depleted, so a reasonable amount would have to be donated now and then.)