Concerning wireless systems, if you happen to be in an area near other wireless networks the interference will be ever present.
I am using a wireless & having good luck with it, but I extended the cable lengths & moved the Transmitter closer to the Monitor & it now works perfect. I did run the cables along the frame rail & up between the cab & bed with loom & in through the rear slider window, so the transmitter is just inside, mounted with adhesive Velcro. I also connected the hot lead & ground at the left rear tail light assembly. The hot is connected to my "tail/running" lights. I prefer this over connecting to the back-up lights, as all I have to do is turn the running lights on & I have constant power when hitching up. I use the power switch on the monitor to turn it on/off or just turn the running lights off. Cmaera is a Refurb Yada on Ebay for $54

Painted the lip of the TT tongue to help.

You can see the yellow lip of the tongue lines up with the yellow marker on the monitor & that tells me the ball is directly under the tongue perfectly.
