Yes is it possible to a SUper character .For leveling alternative combat class you should do mostly fate or dungeon. (you get 50% exp for leveling an alternative class). For crafting class you should spam leve as soon as you reach lvl 30 since they give huge amount of experience and you could do 30-50 with 100 allowance.

The only problem having multiple combat class on one character is the myth tome limit that is currently capped at 300.