there's no rom (comparable in a way to a linux distro) above 4.2.2 - I believe we're missing some of the hardware sources to be able to compile a version of 4.3 or 4.4 for it ourselves, though my understanding may be slightly wonky on that.
there may be another way to acheive a restricted user type environment, what are you aiming to do?
you'll probably have more luck searching more generally for something to remote control an android device - this forum is fairly quiet and any solution that works on android 4.2 should work on the hudl :)
here's the original hudl partition map (starting address and length):
./rkflashtool-linux r 0x00002000 0x00002000 > hudl_misc.img
./rkflashtool-linux r 0x00004000 0x00004000 > hudl_kernel.img
./rkflashtool-linux r 0x00008000 0x00008000 > hudl_boot.img
./rkflashtool-linux r 0x00010000 0x00010000 > hudl_recovery.img
./rkflashtool-linux r 0x00020000 0x00020000 > hudl_backup.img
./rkflashtool-linux r 0x00040000 0x00100000 > hudl_cache.img
./rkflashtool-linux r 0x00140000 0x00002000 > hudl_kpanic.img
./rkflashtool-linux r 0x00142000 0x00200000 > hudl_system.img
./rkflashtool-linux r 0x00342000 0x00020000 > hudl_factory.img
I think my first step would be to see if your partitions match these. It may be possible that Helios has changed the partition sizes - I can't say I've tried using the Helios rom.
I'm afraid I'm not very familiar with windows, and as such haven't used RKbatchtool - only RKflashtool on linux. It maybe worth picking one tool and sticking with it? Though I thought they were both executing the same command line tools, just on different OS's?
What build version are you on currently (settings > about tablet)? When the hudl update 1.3.1 update was released (build no. JDQ39.20140424.153851) I compared the updated SystemUI.apk to the original that I modified and there were no changes. As such, I've been using the modified SystemUI.apk on this build with zero problems.
If you're currently on the 20131016.200812 build then the update is likely to be the 1.3.1 update. If you're currently on the 20140424.153851 build (which I believe is the latest) and you're receiving an update I would be keen to know!
To update, I would put the original SystemUI.apk back, then once updated replace it with the modified one. The update is likely to fail with the modified file in place. You may well have to re-root once updated to be able to push the modified file into place