Thanks for the tip, 12volt. I'll add those to my Christmas list.
Our tow vehicle does great, Phyllis. It still manages to have some pep with all that weight back there, and only shows minor strain on the big hills. However, I'll add we've not ever approached our maximum capacity for weight.
2014 White Hawk 30DSQB Summit Edition
2007 Ford Expedition EL 4X4 5.4L gas with 3.73 rear