Now, it's past 1AM, so I'm not thinking that clearly, but... I built an E6 wizard that kills standard ECL20 fighters.
As you already mentioned, immunity to mind-affecting completely nullifies your strategy. The item Third Eye Conceal from MIC, 120.000 gold, grants you:
A third eye conceal protects you from view
by all devices, spells, or powers that detect,
infl uence, or read emotions or thoughts,
as well as those with mind-affecting or
scrying descriptors. It even foils bend
reality, limited wish, miracle, reality revision,
and wish when they are used to affect
your mind or to gain information about
you (however, metafaculty can pierce the
protective quality). In the case of arcane
eye, remote viewing, or a scrying spell used
to scan an area you are in, the effect works
but you simply aren’t detected.
So, blanket immunity to anything mind-affecting, up to and including Wish and Reality Revision. Nice.
But even if he didn't have blanket immunity, a a Greater Crystal of Mind Cloaking embedded in the armor would grant a +5 competence bonus against Mind-Affecting, and allow a re-roll once per day. Granted that will saves are a fighter's worst save and the crystal is only 5.000 gp, i'd wager it's a very good idea to get one, as it basically saves your ass from a save-or-die once per day. Pretty good for 5.000 gp.
The "Mindarmor" armor enhancement grants you +5 to Will Saves, for one turn, up to 3 times a day, as an immediate action, for only 3.000gp.
A Mindvault is a 8.000gp circlet that 1-day can negate any mind-affecting spell as an immediate action - strictly inferior to the crystal, but still able to negate fully the effects of any one failed save, so that's nice.
Spell resistance can also hose the Wizard, if the Fighter can get it high enough, as will Antimagic Field.
You also seem to have assumed the Fighter will be at melee range, when fighters can be very proficient with ranged weapons. If he specializes in them, the Wizard is hosed if he doesn't win initiative because he'll be unable to get far enough away from the Fighter that he'll be unable to hit him with his incredibly overpowered compound longbow & magic arrows.
Or, even if the fighter isn't built for ranged combat, nonproficiency is only a -4 modifier, meaning you can throw your sword with a 10-ft range increment with a -4, which probably would still be enough to hit the Wizard except on a 1. If he's farther than 10ft away, you can throw it farther with a cumulative -2 every 10ft, which isn't too bad.
