How far are you comfortable traveling?

I'm 30 weeks now and my SIL just told me she wants to plan a shower for me but it would be a 5 hour drive away. Am I crazy for wanting to say no? I feel like it's too last minute/ and I'm too busy, plus I really don't want to go that far away. Maybe if it was this weekend haha but it seems too late to just now start planning. Am I being rude if I say no thanks?