I have the GM accy camera system on my 2015.5 duramax. The rear wireless camera was pretty iffy at the back of my 35ft trailer, but the wired camera worked fine.
The newer system should be much better based on reviews I've seen. Now one spec that I saw said that the feature to "remove" the trailer from the rear view (make the trailer disappear) would only work with trailers less than 35ft overall. that may be where the 35ft came from.
2011 Keystone Outback 295RE
2004 14' bikehauler with full living quarters
2015.5 Denali 4x4 CC/SB Duramax/Allison
2004.5 Silverado 4x4 CC/SB Duramax/Allison passed on to our Son!