before i start talking please take everything i say with a grain of salt because i have no idea of how your states national guard works and may differ from what ive been told by a recruiter
if you did the split training option (basic between your junior and senior year) you would still be doing stuff on the weekends during the school year, you just wouldnt do mos specific training.
but you might not be able to do that because both 12bang bang and 19d are osut meaning that you dont have ait, you just have a longer basic training where you get taught everything at once
most states also offer rsp (recruitment sustainment program) so you would still get to do that 1 weekend a month thing leading up to your ship date, regardless of what path you choose to do
i probably didnt answer all your questions but im awful at this kind of thing