Would I be able to lessen the glycemic jolt by adding some peanuts to the fruit?
Yes
Also, do peanuts cause much of an insulin spike if eaten by themselves or with some other carbs?
No.. Peanuts don' t have a lot of sugar anyway.. unless they are honey roasted. Any foods eaten together, unless it' s a box of candy, is going to lessen the insulin reaction.
Combining your fruit with other slower proteins isn' t a bad idea.
I often eat them at night with my pre-bed snack of cottage cheese. Is that a good combo for late night?
Sounds decent. Cottage cheese is great.. I eat it for breakfast. Peanuts are a good snake in moderation. And you do need fruit for overall general health. So combining it with other foods is a good idea.