I am glad you got it fixed. I was about to say you must have a bad connection to the trailer or a bad ground.
For those reading on this post in a few years, I had my P2 in my Tundra for two years with the bluetooth for the radio on always and never had an issue. I think the RF warning for the P2 dates back to the P1 when guys were running CB radios with linear amplifiers. Some of those were strong enough to make peoples fluorescent lights flicker!
Current TV:'14 F350 Lariat CrewCab, 4x4 Short Bed SRW Diesel w/ Pullrite 2700 (16K)
Current Fiver: '15 Puma 295BHSS Anniversary Edition
Past TV: '13 F150 HD Payload SCrew EB, '08 Tundra CrewMax 5.7L, '02 'Burb 5.3L, '97 Dakota 3.9L
Past Trailers: '09 Wildwood LE 27RB, '02 Palomino Yearling RL, '87 Jayco 1006dlx