Just an update on this. With Luddite's clever suggestion, I've made a lift to help with installing rear wheels, especially when the bike is quite high off the ground, as when using an Abba stand. I got two of the inflatable wedges cos they seemed like useful things for all manner of jobs! To ensure the wheel was supported in a stable fashion, I hinged two bits of board together and popped one wedge between. Obviously, one needs to do the toecap shuffle to get the lift beneath the wheel and the dimensions required will differ from one bike to another, but it was very pleasing indeed to be able to gently pump the wedge up until the wheel was perfectly in line to feed the axle through. Doing it this way should also prevent damage to the thread of the axle and/or the bearings and spacers that can happen if one uses too much force.
Job done!