Sports shooting help (D90)

Yes, this is the first time I've really felt my 18-105 was too short. Since my daughter wants to re-up for the fall season, I was wondering whether that would be excuse enough to grab a 70-300.

As this is youth soccer, half-field, I also can get close-in sideline shots, however. I'm worried 70mm is too long for those. Any experience with these situations would be appreciated, too!

(Please don't recommend a second body and a 17-55!)