How long will these bars keep? I'm thinking about sending these in the mail. Thanks!

I just answered a similar question on hotline regarding a chocolate torte. Here too, I'd be weary. With something like pumpkin, I'd be inclined to refrigerate it, leaving it out for a day, perhaps. Ice packs will melt, so unless you are overnighting, I might go with something else.

You can ship with a freezer pack, mark the outside 'perishable' and warn the recipient that they are coming. That doesn't answer the real question, does it? (Depends on how far, how long -- at least you probably have the weather in your favor, but shipping facilities and trucks will not be refrigerated.)