To be honest, I would check with her doctor. I have been insulin dependent since 1981. I always refrigerate my insulin until it is opened - then it remains in my purse or on the nightstand until I change bottles. For the duration of the time I am using the bottle, I have no problems.
When were there this summer my unopened bottles stayed in the fridge (you could leave at the front like suggested), my others stayed right in the fanny pack and on the nightstand. When I got home I just switched to 2 new bottles since those had been subjected to the hot weather for 2 weeks.
Again, this can be totally dependent on what types she is using and what Dr. says. Over the years I have used Regular, Lente, Ultralente and now am using Humalog/Novolog & Lantus.
However, do make sure that fridge/cooler has small bottles of juice in case she need something to get her blood sugar up quickly. One thing I find handy if I need a quick fix- a can of ready to spread frosting! If I am out of it, its even easy for the kids to stick a spoonful of that in my mouth vs a bottle of juice.
Also, make sure you get a duplicate prescription write-up from her Dr to take along with in case you need it. Some insulin prescriptions (such as humalog & glucagon) cannot be purchased over the counter. In some areas you cannot buy syringes over the counter.
So just have a talk with the doctor - you guys will be fine!!!!!!!!