I personally find the risk in TA well worth the reward considering I collect more resources per gather.
This is an incentive to the skiller to gether here rather than in the safety of the non pvp zone but come with the obvious risk.
Introducing a limit cap on the area of +/- so many levels would only cripple TA as a pvp zone for those who enjoy it.
I would suggest 2 possible solutions:
1. increase the buff on lower players so that they are more powerful (stat wise) in comparison to level capped players.
This would mean that while they have less effective skills in combat, they would pack more of a punch, especially since a lot of the PK'ing involves level 45's bulldozing their way around the place.
2. Add a gatherers shield to a player who gets attacked while in the prone state of being mid gather. The shield would block all damage taken for 3 seconds: This is the length of time lost through animation while transitioning into combat. This would give the player being attacked 3 seconds to prepare the skills/gear to fight back fairly (may have ax/pickaxe/fishing rod etc equipped)
With both of these said, I still stand of the opinioin that this is a PVP zone and any limitation applied to the PVP mechanics is a step in the wrong direction.
If you absolutely hate PVP and want to skill in peace, stay out of TA, you can successfully level your way up in skills without needed this one particular zone to do it