the trimble guys likely know better. but i would suggest the tsc5 might be slightly better. it only has the one usbC port at the bottom and this has a cover. i don y think the 7 has a cover and has at least 3 ports.
we have made simple computer covers for bathymetric surveys using clear vinyl and a couple stitches on a sewing machine. not water proof. but would keep bulk water off. something like this with maybe a soft clear material on the keyboard might help.
i will say access is nice because you can do almost everything with the keyboard(except some line offset commands….and a couple other things). but trying to work without the screen presses would also help with a cover on. because we are in the north you get better at it when forced to wear heavy mitts. i do think the trimble team could make a few improvements here. the tsc5 has more hotkeys, but software like field genius i think allows every keyboard button to map to a command. this helps a lot with mitts.