I’m glad you posted the pictures. I was going to mention how light trucks are being used in the Mid East in that fashion.
As I see it an “ultra-light” combat vehicle would need several things to survive as a fighting force. First off Numbers, ie. quantity vs. quality. Second an extremely low profile that conversely would need high ground clearance capability. (Look to low-riders for such technology.)
Third, an added reconnaissance advantage. (Look at the pneumatic towers News Vans use to push Cameras and Communication dishes to heights over forty-five feet.)
Fourth, a moderately heavy punch per vehicle. Look at M2 .50 Cal machine guns or 7.62 miniguns. Relatively lightweight with a good punch.
Selected vehicles could have a heavier Punch, Javelins or Tow Missiles.
In any case their small size would necessarily mean that there can be no one size fits all category for such a vehicle. And that alone will cause the brass to have a heart attack. They want do-all be-all vehicles, planes, ships and that’s just the nature of that beast.
Let's go back to the British SAS photo and take a closer look at just what is there and what's not.
vehicles: 4 stripped down 'jeeps'
no wind screens, just bare sheet metal
(no. 4 with MGs facing right barely visible)
weapons: 7 LMGs, 1 HMg, sidearms assumed and at least 1 Fairbairn-Sykes knife.
Fuel: the poor bastards loaded extra jerry cans on every surface they could find. That's really trading armor for speed and range.
Looks like a swift hit and run/recon team to me. Single mission, no add-ons.
A nd the Somali, Chad, Taliban, et al technicals with Toyota pickups follow that model to a tee. Light force, quick attack, no ROEs against larger heavier armed force.
Don't know much about the skeleton dune buggy types the SPEC OPs were using in the early days of Afghanistan but from what little I gathered they followed the SAS Desert Rat model.
Funny how field expedient solutions work until some underemployed surplus to needs brass decides they see career opportunities and swallow them whole. Whole lot of fat tails looking for a dog to which to attach themselves.