Well according to Leonardo di Caprio in that nonsensical piece of garbage fiction, 'Catch Me If You Can', it is possible, with an FBI agent waiting outside the lavatory on a B707, to slide out and climb down into the wheel well and make your escape! *
Don't worry about reality, just write any rubbish with doors and hatches anywhere you want them! Look at 'Executive Decision'. The reading public will never know the difference. Look what broomsticks and wands did for J. K. Rowling!
* Whilst showing a friend around the VC10 at Brooklands, I had a sudden flashback to 31 yers ago and remembered where the secret release catch is that opens up the complete back wall of the rear toilets into the enormous tailcone area. Real jaw dropping stuff to someone who has never seen it!