Not a coach but the path a couple friends in college coaching took always involved starting at a school that isn't as competitive and wasn't what they really wanted, then moving up to a higher ranked school, then trying to move to better divisions. You mention it is jumping to D2. For this upcoming season? Seems like there is a path in college coaching. I would think you always have to start "in the mailroom" as they say. Even if you have to look again you would be starting from a head coach position, ahead of where you are now I think.
Speaking generally and not specifically about this opportunity, I hear you about planning to look in spring, but in college coaching you need to be ready to go when you are needed and the good job comes. Both coaches I know weren't looking, were recruited and took a job and moved within a month, and it turned out good for them. Good luck!