You may also wish to consider registering as a homeschooler. Your state does not appear to have particularly onerous requirements for transitioning to homeschooling, and mandates a fair amount of cooperation from school districts, including access to any curricular or co-curricular activities you wish to use within the district (unlike many states, they reimburse districts for classes homeschoolers take). You can even request their curriculum materials at no cost. It would be up to the district whether they would let you take multiple grades-worth of texts, and let your DCs work through them more quickly, but it would probably be worth asking. You might also ask if they have site licenses for any computer-adaptive instructional packages that you could access.
You would need to notify them fairly soon regarding homeschooling, though, as most states have deadlines in July or August (yours, I think, is August 1st).
