I don't think you're a light armor caster:

• Given that Con is your key ability score, your HP is actually more like a Ranger or a Summoner's Eidolon, who would pretty commonly step into flanking and would be exposed to similar dangers (and you're better off than a Swashbuckler or a melee Rogue, and those are better off than most casters)
• Light armor where you hit the Dex cap is just as high as Medium armor where you hit the Dex cap, so again, you're more like a Ranger or a Summoner's Eidolon: middling in terms of AC (same as a Swashbuckler or melee Rogue and much better than casters that don't hit the Dex cap. Those casters that do meet the Dex cap sacrifice their Con, producing an even bigger gulf in HP)
• Casters don't have Water Impulse Junction, Air Impulse Junction with Mobility, or Lightning Dash to get away both without provoking reactions and without spending an entire action just to Step
• Casters don't have Winter Sleet's action tax for enemies outside of it approaching (Stride to aura's edge, then Balance over to you).
• Casters don't have Winter Sleet's Balance chance to spend actions and even turns: I looked at Archives of Nethys's creatures table for creatures without Fly and without Acrobatics: out of 2604 total creatures, 1065 have neither. An untrained Acrobatics check opens up a pretty darn good chance of a Failure at nearly all levels, in which their action is wasted and they do not actually move, or a Critical Failure, at which they fall and their turn ends. There's also the 5% chance of the 908 non-flyers who do have Acrobatics to Critically Fail into a Fail at a lot of levels, which is useful on a long enough scale just by itself.
• If a creature fails Balancing, it won't fall within flanking distance of you (unless it has Reach, but Aura Shaper will keep up with the Reach that enemies tend to get as you level). It will fall a square or more away from you (still within your Reach or Throwing Weapon range).

On the diagram: the enemy on the left can't Step. It has to Balance, forcing two possible Attacks of Opportunity and a chance to fall prone where it is and end its turn. Will it do all that just to set up a flank on you for its allies (that only have a single action to Strike when they get to you from outside your aura)--when you're going to get a completely free non-provoking move next turn anyway?

If it does, I'll take that deal.