Gotta agree with others above, 3-4 weeks for round trip from NJ to Calif. and back isn't a great idea, particularly if you'd like to explore sights along the way. DON'T DO IT!!
Give your wife a treat, do a more relaxing trip. She'll love ya for it
. Think about a drive out to the Black Hills of S. Dakota. Once there, park your rig, then sit back and R E L A X!! Smell the pines, enjoy the mountains. Use your tow vehicle to poke around....LOTS of neat things to see and do, from Devils Tower to Deadwood, to Rushmore, to Needles Highway, to Custer Wildlife Loop, etc. etc. ALL reachable during easy, day tours from most any campground ya might pick as your home base.
Steve & Lynette