So what about an M8 or M20 with some improvements? I recently acquired both types in 1/35th scale (Italeri) and was pleasantly surprised at the detail provided within. Unlike the earlier Monogram M8 and M20 kits (1/32nd scale) which are nice but a bit on the clunky side. The Italeri kits appear to capture all of the fine details but fail on the M2 Browning .05" heavy machine gun which is a problem in almost every Italeri kit I have encountered so far.
Of course you could build the kit straight out of the box and just add the markings of your own choosing but I would like to take it to another level by adding an M151 Remote Weapons Station from AFV Club (Stryker accessory set) or maybe sacrifice one of the 25mm Bushmaster remote weapons stations that was offered in the first issue of the Tamiya HMMWV kit. I like either one and the Bushmaster RWS will certainly take up a lot more space in the vehicle. With what I have in mind the fighting compartment would need to be fitted with a roof and a couple of access hatches added. Of course this all depends on which version you are using and keep in mind the M20 does have a raised superstructure/bulkhead surrounding the fighting compartment while the M8 does not so additional height might be required to get clearance for your remote weapons station.
Here are a couple of images of the M8 and M20 to ponder:
M8 Greyhound on display somewhere in Connecticut (2008)

(Larger image available for viewing by clicking on this image. Image source:
Wikipedia/Minnesota Historical Society)
M20 Armored Utility Vehicle on display at the U.S. Army Ordnance Museum, Aberdeen Proving Grounds, Maryland

(Larger image available for viewing by clicking on this image. Image source:
Wikipedia/Mark Pellegrini)
Wikipedia M8 Greyhound/M20 Scout Car