I did something recently which is exactly what you need to do this. You have "virtual gauges" which can be configured (colors, size, position, etc) and placed in a window/on a screen. It includes 7-Segment displays as well as analog gauges, rpm-bars, etc. Maybe I find some time between christmas and the new year to get it to a releaseable state.
oh good god I'd love to have something like this...
ever since I fried the touchscreen controller for the 8" that I was gonna use for my carPC, it's been sitting at home doing nothing but light multitasking
One problem that I see is if this is used on a secondary monitor and not a networked client, using a touchscreen for buttons and settings/whatnot might change focus from LFS.exe to the external app and create some issues there.