I finally found drawings (side, front and overhead) for a Wickham Trolley in an old issue of Sixteen Millimeter Today. While probably not sufficient for rivet counters, they suit my level of modelling. I have now blown them up by 140% for 7/8 scale, two feet on 45 mm. (The SMT author blew them up from 7mm to 16 mm and narrowed the gauge to two feet on 16 mm.)
If anyone at Diamondhead wants a set, I'll have some copies. My @#$%^& (*&^% "all in one" works fine as a copier or printer but refuses to scan, so I am not presently able to send them out electronically.
Lightlines makes (or made) a similar kit, but it looked too flimsy for my rough handling. I am using an LGB motor block and 4 AA batteries. DPDT switch for reversing, but nothing so complicated as speed control.
Mine will be more "in the spirit of" than prototypical, but the variations in the prototype are so wide that nearly anything is possible. Consider a couple of Rob's X-rated honeys and some bottles to make a "Comfort Wagon"? The last remains of dying passenger service? His lordship surveying the estate (w or w/o a honey).
Anyway, if anyone is interested, let me know and I'll try to share.