While storing crackers this way is certainly better than not, I would suggest two things: first, I don't see much reason for using an o2 absorber with a foodsaver bag especially since I wouldn't expect you to store these crackers for decades and, second, consider storing crackers that have very low fat content to reduce the possibility for them going rancid. I would also encourage you to mark the date you buy/pack each box of crackers and rotate them.
FYI, silica gel should not be used with oxygen absorbers because the oxygen absorbers require moisture to do their job. Silica gel can be used for purposes where moisture is the bigger concern such as with ammo. So long as food has been dried sufficiently before storing, oxygen is the problem, not moisture.