My child who was grade skipped was skipped at the suggestion of the school so I don't have experience in doing that with an uncooperative school system. My 2e kid isn't and won't be fully grade skipped b/c it is not likely the best thing for her. She's also already "too young" for grade b/c we got her in before the cut off by starting her in a different district.
The only part I have some experience in is your #3 option. Our school system does offer subject acceleration in math but they have been seriously tight gate keepers in the past on that one. We were told previously that the kids needed to be selected in 3rd grade and, if they weren't, they would not be eligible for acceleration. We were also told that they needed to hit the 98th percentile on all measures and one being too low would disqualify them. I believed that line when dd12 was a 4th grader and came out at the 97th percentile on the MAPs test at the start of the year and thus didn't qualify despite numerous other qualifying scores in IQ, etc. She learned nothing in math that year and spent a lot of the year helping the other students. Math is her weakest subject so she should never be in that spot. She skipped a full grade the next year and, despite dire predictions for how kids who didn't hit that magic 98th percentile point by even one point on the MAPs would flounder a year up in accelerated math, she's been a straight A - A+ student in everything including accelerated math.
So, here we come to dd10, who is HG and 2e. Her achievement scores fluctuate like mad. I knew that the wild fluctuations would likely disqualify her and she was placed in regular 5th grade math with no enrichment at the start of the year. Our school system now also has a policy that a GT id doesn't mean GT placement if you aren't a consistently high achiever. She's too much of an underachiever for me to let it slide like I did with dd12. She won't get back on track as quickly if we waste another year with her and she's had too many years in school that have not worked for her already.
She was already in the GT teacher's class for an hour/day for reading and the GT teacher generally likes dd despite me being a real pain at times ;) . Dd was upset about her math placement and I wasn't good with it either. I let the principal, the GT teacher, and her homeroom teacher know that this situation wasn't working. Combined with the fact that socially school has never been a good fit for her and her class size was huge this year (12 kids larger than 4th grade was), the math issue was kind of the straw that broke the camel's back. She was either going to be placed somewhere else or we were changing schools or homeschooling this year. She was moved to the GT teacher's class for math as well and is doing 6th grade math this year. It was supposed to be a tiny group of a couple kids and has grown to quite a bit larger I'm sure b/c other parents are good advocators as well or we all complain a lot ;) .
I believe that has she passed the test she was given to continue with subject acceleration of some sort in math in middle school.
