It might be possible with a USB2.0/OTG enabled tablet. OTG stands for On-The-Go. It's a protocol supported in Android 4.XX that allows you to connect USB devices to some tablets.
Samsung enables it on their Galaxy line (technically you could use it on a Galaxy SIII smartphone afaik) from what I've read they're one of few mfr's that enable output file sharing also. The Nexus tablets have OTG but it's only to add external mice/keyboards. The Kindle Fire's don't support it at all.
The cables are sold for a few $ on Amazon. My buddy has a Galaxy Tab 10" and we were able to transfer MTS files from his Canon MF200 to it. There's a USB/OTG file mgr needed, it's called Stickpoint? or Stick-something. It's on the Android Market.
On my buddy's tablet, he also has a removable microSD slot so you could then transfer files to that. I don't really see why you couldn't also transfer all the files from the camera to the tablet then plug a flash drive into the cable and move them to it.
Somewhere I've read that you can't use a FAT32 portable hard drive though as it's incompatible with the Android OS. But IDK if that's true, I have a Kindle Fire with a USB cable - when I plug it into my computer, I can copy files from an external WD drive I have installed. But it's possible the Kindle O/S (Android 2.2) handles that for me and Win7 handles the disk I/O.
Also, unless it's changed in Android 4.2, I believe there's a 4GB file size limit you'll have to deal with. It would seem to me that in a pure transfer, that wouldn't matter but IDK.
Personally I like the netbook idea. A 10" netbook isn't much bigger than a 10" tablet, and they're cheap now since tablets are dominant. There's an Acer (slower processor) with 1GB ram and a 320GB hard drive on Amazon for $229. If you wanted it even faster/more battery life pay someone to swap an SSD drive into it. They're in the $150 range now.
The 7" Galaxy is $200 so by the time you add storage media, the netbook is cheaper. Either has wi-fi, with the OTG cable you can add cellular service to either also if your phone is compatible - or if it functions as a Wi-Fi hotspot you don't need the cable. I don't use Stickpoint, I use WiFi File Express - as the name indicates I can transfer files wirelessly across my network to the Kindle. Never tried from it though.
hth, let us know what worked for you.