If you want to try Linux (Ubuntu) on your MK802IV or T428 device without multiple flashing or SD cards, please try this approach.
A Windows PC with Rockchip's standard firmware upgrade application "RKAndroidTool v1.37" and "7-Zip" installed.
loader: (MK802IV) https://docs.google.com/file/d/0B99O3A0dDe67WDNmU2ZHR0NVb0U
Recommended packages to install include "ssh openssh-server tightvncserver cpufrequtils chromium-browser".
Many thanks for all the earlier feedback that inspired this approach.