Maybe I'm a little confused about what you really want to do, but I'm guessing that any reasonable tablet will work. For example, I've used an iPad Min Gen3 (circa 2015), iMove, and a SeaLife Micro while spending a week in Cozumel. My biggest problem was the wifi/internet, not my hardware. I added a bluetooth keyboard/case so I could write content for my blog while traveling. Read my blog's earliest posts for details about the hardware. The blog also has a bunch of videos I made and uploaded from the iPad while in Cozumel:
Jeff's Cozumel Scuba Blog
Tablet processing power has increase and costs have decreased since then. I currently travel with a Lenovo Tab2 A10 -70F, which is quite old. I think a 10-inch tablet is a good balance between price, usability, and size/weight. I have also used 'Videoshop' on my iPhone 6 with great success. I would guess that any middle-of-the-road andriod, like the Samsung or Lenovo would be fine for video editing. The newer Lenovo Tab4 would probably handle the work without issue, and is only $160 on Amazon.
If you are the type of person that starts the gopro when you splash, and records continuously until you surface, editing on anything (even a laptop or desktop) will be a slow and difficult process.
If you take frequent
shorter videos, you might not even need editing software. Just delete the videos you don't like and keep the good ones for later editing at home.
Oh, and I've traveled all over the world for work and never had the TSA force me to check my laptop. The rare exception might be if you are taking a tiny puddle-jumper from island to island, and there is no room in the overhead for your large carry-on, but even then you just hand carry your laptop separate from your bag for that 1/2 hour flight (see
Alaska's a la carte as an example). As far as someone spilling on it, just don't use it on the plane.
@shmuggy I think your fears here are unwarranted. I sometimes vacation without my laptop only to reduce my carry-on weight and size, not because I fear drink spillage or TSA.
EDIT: I just watched the videos again, and wow have they been compressed! I think youtube did a lot of the compression, and I also did some on the table to speed the upload. However the tablet software also had a lossless output option.