I owned a Stimson Mini Bug Mk1 during the late 70's.
Stimson Mini Bug Mk1
The car was registered on 31st December 1970 as NSX707J.
When I bought the car (for £80) the body was in a very bad way and ended up on a bonfire.
However I did use the chassis on our smallholding for towing a small trailer (see picture above).
A previous owner had cut out the top chassis tubes from the dashboard back to the rollbar.
As a result the chassis was a bit flexible!!
A Mk1 850cc Mini engine was fitted (I appear to be having some carburettor trouble in this picture)
(I also appear to be having some style trouble - note the 'flares' - well it was the 70's).
Mini Bug Mk1 Previous Owner
Not only did I have flares but the bug had been fitted with wide flared arched to accomodate oversize Cosmic alloy wheels.
(Compare the picture above with Barry's original creation below).

The Mk1 Bug did not have the lower body mouldings, screen surround moulding or the roll over bar moulding,
which were fitted to the Mk2s.
The Mini Bug used a Mini engine/gearbox and subframe at the front and had Mini trailing arms with coil-over-shocks at the rear.
There was a square section, spaceframe chassis under the glassfibre mouldings.
Barry Stimson
Barry Stimson - the originator of the Mini Bug, the Scorcher three wheeler, the Safari Six (six wheeler) and the Trek.
Stimson Mk1 mini bug chassis
Above) Some original Mk1 publicity photos from
http://www.miniplanete.com/04decouvrir/01histoire/05special/01kitcars/stimson/minibug/minibug.htm
Stimson Gallery
Mini Pages