Summer family get away with an infant? 🤔🤔

li
So my daughter is due to be here on April, 11.. my MIL keeps saying that she wants us to go visit her side of the family in Corpis Christi this summer (9 hour drive from Dallas), but my daughter will on be about 3 months old. I don't want to take her and I've made up my mind already, but she keeps insisting the baby would be fine and begging us to come. Plus, even though her side of the family is super nice, I don't feel comfortable going somewhere I've never been with a new born... 
when was the earliest you took your baby on a road trip? Or a trip in general..