Agree with David, although the distinctions are blurring in some cases.

RE Wacom tablets, I had one for a while, sold it. It was the 'standard' Intuos model (medium size), worked fine but just didn't find myself using it much. A Cintiq model might have been more attractive, those are the ones with a display that you draw on.

I previously had a 13" MacBook Air that did a good job with RAW editing, and was great for travel. I wouldn't want a screen smaller than that, though.

The 13" iPad Pro is something I had considered. I have the 9.7" version (along with a Brydge keyboard that makes it like a tiny MacBook), and the Apple Pencil is far superior to most touchscreen/stylus combos - as sensitive and responsive as the Wacom tablet, but you're drawing on a high-resolution display. What put me off the iPad as an editing tool is that it doesn't truly edit RAW files, only JPGs (might be fine for trips, but you'd have to re-perform those edits on the RAW file at home). However, there's hope on the horizon since iOS 10 will support RAW images from the onboard camera, and I expect that will eventually lead to RAW support for external cameras, too.

Ultimately for me, I don't generally do photo editing on trips (even though I generally have my 17" MBP with me) – during the trip I'm either out and about (business, sightseeing and/or taking pictures), or sleeping. I save the photo editing for home.