Are spores an issue in sauteed pepper storage when you add garlic?
It seems that temperatures in excess of 250°F for an extended period of time will destroy a significant percentage of the botulism spores but I cannot find a definitive, science based answer on botulism spore death.
Acidifying garlic can take three days to one week when stored in vinegar, so I would assume the pH will not carry enough weight.
As long as it's in the refrigerator, you've got a few days, at least.
How much are you making at one time? You can freeze garlic in oil and keep it for months that way. Googling suggests that freezing peppers in oil is a common technique, too, so you should be able to store the entire thing in the freezer for months. You could make a large batch and freeze them in ready-to-use portions and be confident that your food is safe.