That would definately affect the sensors. I have a bike carrier on the hitch and the reverse warning beeps will go off continously when in reverse but luckily they can be disabled by a switch on the center console. The backup camera of course will not be affected.
Mine does the same with the bike carrier. Would've left it on had it not been for that. There must be a way to re-calibrate it to accept whatever's back there? If it exists I haven't come across it. Will have to go RTFM.
It's just sonar. If it gets a quick return on a ping, it raises an alarm. There's no way to distinguish the return off the bike rack from other returns.