Not sure why everyone wants leeanne upped so quickly.
I pretty much ran straight to desert maps by lv50 with 3 CC units. Bashira+Katie+Iris.
Granted, i knew what i was doing and DMM has no shortage of silvers. (plan was to skip leeanne entirely, and it worked out)
That said, you'll still need leeanne in nutaku for lack of a better replacement. Hopefully the end of the year we'll have a gold rush with bernice.
Source: Leveling new account on DMM (1 month old)
Katie pretty much covers as a tank till the harder maps.
Soma can be skipped if you are close to spica (>100+ DC) -> I would advice a VH to replace as the 3rd range dps when you need one