The Skill Mastery point has already been covered, but the Skill Artistry bonus also won't work. It's a competence bonus, and hence won't stack with the OP's custom ring. Nor, for that matter, with the +4 a Truenamer gets for speaking his own personal name.1 level dip in Exemplar would suffice. +4 to Truespeak checks, and choose it as your Skill Mastery, and you can now take 10 on it.
My biggest beef with the class is that a class really should be viable with the basic resources available to it. You ought to be able to make a decent Truenamer with human as your race, the elite array of ability scores, and no books other than PHB and ToM. Within those constraints, at level 1, you'll have a Truespeak check of +10 or +12 (+3 Int, +3 Skill Focus, +4 ranks; another +2 for targeting yourself) versus a DC of 17, and at level 20, you'll have a check of +48 or +50 (+11 Int, +3 Skill Focus, +10 amulet, +23 ranks, +1 Luckstone; another +2 for yourself) versus a DC of 55.
I'm a teacher. When I'm grading a test, if a student bombs absolutely everything else, I'll still give him a point or two for getting his name right. An out-of-the-box Truenamer can't even manage that, 20% of the time. That's pathetic.