You could use fighter insted for one level and a single feat but you would still pay for point blank shot to get precise shot (not bad with spell perfection but its already a feat heavy build) which would allow you caster level 18 before traits and give you access to ninth level spells Throw in two levels of divine hunter paladin for free precise shot and cha bonus to saves, it also lets you smite 1/day for adding cha to your to hit and a little extra damage (+6 with the bracelet).

Take either a primal elemetal bloodline, a dragon bloodline or crossblood both.

I'd go the eldritch knight route with weapon focus, weapon specialisation and improved critical. This would be one of the truly rare corner cases where I'd even consider 'toughness' as a feat. Even at low levels you're going to be pretty hard to hit, so get on in there and touch to your heart's content. So some +1 studded leather, with a ring of force shield, ring of protection, amulet of natural armor, maximum dex score, belt of dexterity, dodge feat and a wand of barkskin. You can wear armor, there's even a feat which reduces the penalties you take for wearing armor, but I've had melee touch casters who just eat the spell failure chance.

If you want to build a true melee touch attack sorcerer or wizard, you will need to focus on AC and dex (which helps with AC). I see someone finally mentioned spectral hand. First is to cast the spell and touch with it immediately, the other is to hold the charge and touch as part of an attack against normal armor class. You can avoid attacks of opportunity with touch attack spells two ways.

Bouncing spell and ranged touch spells