I put mine at the head of the bed on the inside and blocked from my head by a pillow. Never had a problem.
I ALWAYS travel (car, plane, train, cruise ship, overnight ferry) with an extension cord and 3-way plug thrown in the CPAP bag. I usually take my battery pack (it is wonderful) and run the CPAP off it almost everywhere I travel (including Red Cross Disaster Team and all train trips since I got it) to avoid having to worry about plugging in any more. It lasts 3 full nights w/o the humidifier and 6 hours with it although I leave the humidifier home for any trip less than a week. I charge the battery pack about every other day when I use it w/o humidifier so I know I always have at least one more night of charge.
Battery pack cost me $300 (whew!) but was money well spent. High quality lithium ion battery pack so I can use it in case of power failure at home. Also charges or allows me to run any 12V device and will charge my cell phone. Comes with 12V "cigarette lighter" hole and 12V plug for it with all sorts of connectors. Nice for CPAP on train or in so many hotels where outlets are at a premium or inconveniently located. I just put the CPAP on top of it on the bed between me and the wall.
I went in for a checkup with my VA doc. He asked me about portable power for my CPAP. When I told him, he looked it up with Google and ordered one right then for himself as he uses CPAP too.
I have started making trips w/o the 110V to 12V adapter and just carrying the battery but I have never taken it on the plane. For our first plane trip (to Alaska next week) in a long time but I will leave it home as for a 3 week trip, I'll take humidifier so power supply will work best.
If anyone is interested, PM me and I'll try and find link to best deal I found when buying it. Can be bought directly from Chinese mfgr but not a bargain unless you find 9 (or 49) friends and the distributors might give you same deal for the 10 quantity.