Well, the easy solution is get a CA3 and hook it up. This gets you automatic power rollback on overheating and all the other CA stuff.
But, a DIY approach is to get a programmable (y = mx +b) meter and set up the m and b coefficients for the KTY-83. You will still need to address a weatherproof case, DC/DC converter, mounting gizmo, etc.
A Sure Electronics ME-DV31423
Red LED 10V Multifunction Panel Meter should do the job. See:
https://www.parts-express.com/me-dv3142 ... r--320-536
You can pull the requisite parameters from the KTY-83 datasheet.
Teslanv (very reliable source) indicates that the Mxus3K uses a KTY-83/110.