Just wanted to give an update. The manager of the RV park where they are staying has offered to drive the RV to Houston at no charge. The in-laws have gotten to know him well since they've been there awhile with FIL's sudden medical condition/surgery/rehab and they are comfortable with him driving it to Houston.

Thank so much for everyone's replies and ideas, and thanks to you especially rkkwan for your generous offer. I sincerely hope to meet up with you one day while I'm in town.

Glad it worked out. There's so many nice people in this world :-)

Wonderful news, Statia, and what a relief it must be for you and your in-laws to have someone they know drive the RV. I hope your FIL is doing well. Thank you for reporting back!

Glad all worked out well for your FIL.