I'm looking for input/comments:

I will be taking road-trip of ~3-4,000 miles in August to visit relatives.
My wife and 2 dogs are going. I had planned to rent a mini-van (ugh) to save miles on my V70T5 and for more space. The thought crossed my mind: why not use my wagon and get a rooftop luggage carrier (never used one of these) as I have the luggage bars on the car?

1) What are the pros/cons of using my own car and putting on the mileage? I'll break 100K next couple weeks. Just did 97,500 check at dealer, all is fine. Car has been running better than ever with recent ETM software upgrade. New tires ride great.

2) What do I need to know about using one of those rooftop luggage racks:
How does it change handling/mileage, etc?
How sturdy are they?
Security at hotels overnight?
Where rent?
How much $, etc?

Mini-van rental would be ~$900 at Dollar Car Rental. Could pay for my timing belt with that money.

All things being equal otherwise, I would greatly prefer to drive my T5 rather than a mini-van.

All comments appreciated. Thanks.