Someone on the ABR site recently listed a Samsung Galaxy Active rugged tablet and Brodit locking mount that they had bought to fit to their bike and use as a GPS unit.
I have this set up on my GSA for riding offroad and have had it for about 12 months now.
The samsung tablet is generally very good but I don't believe they make them anymore.
The standard sat nav holder with the contacts removed fits a circular disk ram mount and using a short arm will connect onto the brodit mount.
To make it work as a sat nav you;d need to use google maps and download the offline maps or buy the tom tom app or something for what ever cost per year.
I used viewranger to get the O.S maps but they provide a UK wide free map (the scale/detail you'd typically get from a paper road map) you can get to most places with that.
Alternatively fit a sim card and use a live data connection.
The locking mount is not very good, it seized on me and wont open, you can pry the tablet out, but Ive gone for non locking this time. I've had no problems with it gripping the tablet.
To provide power you need about 9v I think, so you need to get a female 12v cigarette connection to connect the brodit mount to.
The 12v female connection is via a switched relay.
The male and female cig socket connections are in a piece of inner tube then sealed up with gaffer tape and live in the cockpit area behind the winglets.
I was navigating with google maps the other day it it went haywire doing all sorts, not sure whether it was the rain or voice commands being activated by the wind noise.
I found a setting eventually for turning that off but not had chance to try in the rain again yet.
I don't recommend as a sat nav without a decent offline navigator like the tom tom app. It is however a great replacement for paper maps.
Having a 7" screen display for 1:50k or 1:25k maps provides an easy to read display. Its been very useful for doing parts of the T.E.T.
BTW. most gloves wont activate the display BMW enduroguard have a tactile pads on the index finger which do work.
EDIT:
Check your positioning of the mount carefully before bolting up tight as the brake and clutch reservoirs or mirrors will hit it otherwise.
Also you need the ram mounts to lift the tablet out from infront of your RID otherwise you wont be able to see turn signals, cruise control or revs about 2k or MPH much above 30mph.
Mirrors might also be a problem. Though I've flexi mirrors so they can be flipped up to filter pasty trucks and 4x4's and for tumbles.