If you can't carry your camera gear onboard, don't ... I repeat: DON'T ... check your camera bag.
Items that look like they might be valuable often grow legs.
Pack your Lowepro and your camera gear in with your clothes. The camera gear will be well cushioned and out of view of the casual observer.
If you don't have room, pack clothes and toiletries in the Lowepro, and pack your camera gear in your suitcase along with the rest of your clothes.