See... I think the fishing trip sounds like a good idea!
I happen to love driving, so I'd probably tend to split the difference... Drive her to there, and then go fishing somewhere nearby for however many days/weeks she wants to visit, then drive her home.
Present it as "Letting you connect with your family and have some good quality time with them, without having to worry about my stress level going through the roof and no one having any fun."
LOL... Used to do that with my Ex & his family. He'd visit (why, god alone knows), I'd take zeh kiddo and we'd go road tripping & swimming & doing photography stuff in about a 200mi radius (no way in hell was I leaving my kid with my ex's family. Long story, all ugly). <Chuckling>, I presented it to my ex as "You can visit and I won't have to kill anyone" ;) That was my condition on driving out there. I'll drive. But I won't stay. Period. On the upside, everyone on the Rez totally got why I was drifting around, and wouldn't let my kid be around my inlaws. ((Hey for a white chick, you aren't too dumb, are ya? Yah, I'll pass the word. You & the boy are welcome around.)) Seriously not good people my former inlaws. And coming from me that's saying a lot.