I have a 34' 5th wheel pulled by a Dodge Cummins 4X4 Long bed.
I tried to save some $$ by going with the Tadi Bro's 7" Monitor with Built In Wireless CCD Mounted RV Backup Camera. Read a bunch of reviews finally pulled the trigger and was very disappointed. I tried moving the antenna closer. Still crap. Sent it back got the full refund. Their customer service is spot on.
I then bought the Voyager Digital Wireless 7" Backup Camera. Here is a perfect example of YOU GET WHAT YOU PAY FOR!!!
Awesome system. Easy to install. Excellent reception. Clear picture. Great night vision.
I hope this helps and happy Pulling!