I don't know if these will be any use, but try:-
http://remlr.150m.com/jbshed.html
http://remlr.150m.com/dmshedtopless.html
http://remlr.150m.com/mrshed_gbfm.html
The first link look's the most promising for the Gunbuggy
As for the lightweight:-
http://remlr.150m.com/
will probably also provide some answers..