I think it would be better to divide the land speeders in the support squadrons into a 3-2-2 manner, so that you don't have a squadron of 5 land speeders for the opponent to shoot at.
I would also give one of the sergeants (the one with the chaplain riding alongside it)
a powerfist. Just cuz' it's the chaplain squad that is going to want to see some close combat during the fight.
I also recommend taking Sammael on his Land Speeder. The thing is godlike, and also fits in with the large amount of speeders already present.
The day you met me may have been the most life-changing day of your life. For me, it was simply tuesday.