How high is your "high voltage"?
Why do you need to match these two devices?
It seems that "huge" size is required to make Rdson low, and to handle large currents.
Please note that while device resistance goes down with its gate width (or area), resistance of BEOL interconnects will go up, and may contribute a significant fraction to the total Rdson - so your mismatch may be caused by interconnects.
There may be other things related to interconnects - like uniformity of current distribution over the device area, current density / electromigration issues, thermo-mechanical reliability problems if these devices are used in automotive or other applications with repetitive power pulsing, etc.
Regarding your layouts - case (2) will definitely save you area, and simplify metallization routing.