I'd start cracking away at those you can do solo. If this is your 1st mythic, remember you'll need to FIRST make Captain rank (beating every assault), and THEN do it all over again with the books. After your 1st, you'll already have captain and not need to do them twice.
These days, there's only about 4 assaults that aren't VERY easy to solo. And of those 4, only about 2 that are truly a pain vs. just fighting the randomness (I'm looking at you, Orichalhum Survey).