Imotekh (Night Fight mainly, but lightning strikes for random fun)
That's 1125 points there. Fill the rest with Warriors and some Ghost Arks.
The Scarabs run around 19-24" (after getting +3 Scarab bases each from the Spyders) assaulting every vehicle in sight while the Spyders try to keep up. If need be, wait a turn to exploit the guaranteed 1st turn Night Fight to set up for the first charge. Remember it isn't necessary to have them rip open every vehicle, so multiassault and get multiple vehicles down to 4ish AV. Next turn, scuttle away to find new targets (or meet the Spyders for more Scarab bases) and let the Warriors shoot their now auto-pen shots into the armor shredded vehicles.
The Scarabs can also tarpit most infantry quite well even if they aren't the greatest at killing them, but used carefully, the Spyders can help on the beatdown. In fact, that is the weakest part of the core of this list, the AI is low, especially if you have to worry about leaving squads at objectives.
Booooring, but it should be workable.