Well, I succumbed at the weekend and got a Wickham Trolley - £65 from the ex-Mr Modelfair.
It is a tiny, delicate thing. This chap's video here gives a good representation of it - you can lose the first couple of minutes.
I got the plain yellow, as seen in the video, that seemed the best to produce a "plausible" version eventually.
It is extremely light and requires a pristine track surface.
There is, as you might expect, no space for a DCC socket, but Hattons will flog you a ready-chipped one for about £110.
The 'gravel' load isn't desperately realistic - a coating of suitable sand might help - and add to the weight.
If fitting personnel, then it could be an idea to use white metal ones, to further aid track connection.