I used the 88p as it came out of the box. No extra gauge or valve at the tip. There is no reason for it. The only minor change I would make to the 88p (or similar) is to put a clamp fitting on the hose rather than the screw on fitting mine had.
I have since built a York, and use my inflator deflator contraption with it, but only in the inflator mode. It cannot be used on the 88p or TMax for the reasons discussed.
In order to use an inflator valve and gauge at the end of a hose, the pump must have a pressure cut off switch or have a large enough reservoir to avoid over pressurizing the pump while taking a tire reading.
I just found this one: https://t-maxwinches.com.au/product/t-max-tyre-inflator/
It mentions in the description: Air up – Connect to your T-Max Compressor and you can deliver it’s insane 160L per minute.
I am really confused now, since the manual mentions otherwise.