[RPG] Starting at a higher level

On the gamemastering page you linked to there are guidelines on what players should spend their starting wealth on.

Table: Character Wealth by Level can also be used to budget gear for characters starting above 1st level, such as a new character created to replace a dead one. Characters should spend no more than half their total wealth on any single item. For a balanced approach, PCs that are built after 1st level should spend no more than 25% of their wealth on weapons, 25% on armor and protective devices, 25% on other magic items, 15% on disposable items like potions, scrolls, and wands, and 10% on ordinary gear and coins. Different character types might spend their wealth differently than these percentages suggest; for example, arcane casters might spend very little on weapons but a great deal more on other magic items and disposable items.

I think the hat of disguise is a wonderful heirloom to start the game with. It promotes roleplaying and fascinating non-combat interactions. In my games I would expect characters to take one of five routes:

1. All characters can get an equivalent non-combat magic item of about that cost given a backstory. Then, if they want an item, they can go to equivalent effort and their choice is respected.

2. You may want to allow each player to nominate a book to involve in the game. In this player's choice, it should be the Tome of Magic. I've played a social binder (equivalent to a gent with a hat of disguise) at early levels for precisely this reason. The character may want to dip into Binder, because at level 1, he gets access to Naberius, which gives benefit to social skills as well as the ability to disguise self at will. It sounds like it fits his intentions perfectly, and there are a number of other capabilities that would benefit him neatly.

3. House rule a feat (due to the paucity of sources. Otherwise I'd use one of the extant ones) to provide disguise self once or three times per day, as per a caster level of the character's level. There are plenty of better things to do with a feat, but disguise self could be worth it to a sufficiently motivated character.

4. Invest heavily in the disguise skill, and some masterwork elves ears. While it's not as exciting as a full on disguise spell, bluff, forgery, and disguise do form the basis of the Rogue's repertoire for good reason. Disguising oneself as another race is a -2 on the check, which can be easily countered by the underwhelming deceitful feat.

5. The character starts out as a sorcerer, knowing disguise self and silent image. Using the fluff that "the magic's in the blood" it's quite plausible that he was casting spells in the crib. The rest of his levels can be rogue, flavoured with just that hint of the "alien, uncontrolled magic that is his heritage"