That's right, Souljourner. One last suggestion-you can check my math ... If he takes that second level of Barbarian early, second or third level, and Fighter levels from 6 through 19, he still gets the thirteen Dragon's Toughnesses he had before, because he can now take that feat with his very first Fighter bonus feat. He'll be giving up his one Troll's Toughness instead of one of his Dragon's Toughness feats for the Wizard and second Barbarian levels, for a net gain of +4 (including the one point from the Barbarian level average hit points replacing the now-useless 15th Fighter level).
1 Barbarian 1 Fort +2 Feat: Toughness
2 Ranger 1 Fort +4
3 Barbarian 2 Fort +5 Feat: Dwarf's Toughness
4 Paladin 1 Fort +7
5 Monk 1 Fort +9
6 Fighter 1 Fort +11 Feats: Dragon's Toughness X2
...
19 Fighter 14 Fort: something ludicrous Feat: Dragon's Toughness (13th: Fighter bonus feats at Fighter 1 and every even Fighter level = 8, Regular feats at every third character level except for 3rd level = 5)
20 Wiz 1, summons toad familiar
1 Barbarian 1 Fort +2 Feat: Toughness
2 Ranger 1 Fort +4
3 Barbarian 2 Fort +5 Feat: Dwarf's Toughness
4 Paladin 1 Fort +7
5 Monk 1 Fort +9
6 Fighter 1 Fort +11 Feats: Dragon's Toughness X2
...
19 Fighter 14 Fort: something ludicrous Feat: Dragon's Toughness (13th: Fighter bonus feats at Fighter 1 and every even Fighter level = 8, Regular feats at every third character level except for 3rd level = 5)
20 Wiz 1, summons toad familiar