Ok thanks what if I just root and not flash a custom rom, would this trigger the knox?
It depends on the rooting method you use. The one I used to root 4.4.2 after I updated via Odin was Chainfire's
CF-Auto-Root and that tripped KNOX because it installs an unsigned (by Samsung) custom recovery temporarily before re-flashing the stock version.
I've never used
Kingo but they claim to be able to root the Note 3 without tripping the KNOX flag so their method using an Android vulnerability to gain temporary root might work for the Note 8.0 as well.
My suggestion would be to use these forums and Google to research all the current methods for rooting the Note 8.0 and make sure there are users who have done it successfully with the KitKat boot loader installed and not tripped the KNOX "warranty" indicator.
Based on the KNOX articles I've read it appears that flashing, or even booting, an insecure kernel can set the eFuse switch which is said to be "impossible" to reverse, so flashing custom kernels and ROM's is out even if you can get root with the stock ROM without tripping the indicator.
I can understand the requirement for KNOX in high security environments but automatically voiding the warranty is just encouraging users to brick their devices in ways that prevent the KNOX flag from being accessed. Perhaps Samsung's position is that once the eFuse flag is set even their service centers cannot reverse it so the device is not able to reconditioned and sold since a tripped KNOX flag also disables some security features in the stock ROM.
Edit: I just read your OP again and if you don't flash the 4.4.2 (KitKat) bootloader and root with CF-Auto-Root you should be fine, even flashing custom kernels and ROM's, and still go back to a completely stock configuration using Odin to install the stock 4.2.2 ROM and TriangleAway to reset the flash counter. AFAIK there is no check of any historical data when the KNOX enabled 4.4.2 bootloader is installed but I would make sure that TriangleAway has successfully reset the flash counter before upgrading just to be safe.
ramjet73