Twin stick 18x4 setup help (Logitech wheel)

[CLETUS]

Alright I started this by calculating out the out put ratios from an 18 speed road ranger and a spicer 4 speed auxiliary. The transmission mad it in game and I can shift through all 72 forward gears and 16 reverses in sequential mode but I have to skip shift to properly shift. Now my question is basically how to add another range select because basically the 4 speed auxiliary is just a range select with 4 gear positions (low,under,direct,over). The 18 speed will be shifted like Normal or would be compounded using the auxiliary. As far as shifting the 18 speed half I will be using an skrs 18 speed with easyjake (or something similar). I will have two shifters wether that be two Logitech (or another that plugs in via usb) they will both have actual shift extensions and the auxiliary will have a curved extension specifically for a real auxiliary transmission and a normal shift knob. So with this all bing said I’d like to get some information and input to see if this is possible before I invest. I’ve already seen most of the how to videos into turning your 18 speed into a 2 stick but they aren’t in-depth enough for me to actually give the project a green light. Like I said input would be greatly appreciated!