In for a penny, in for a pound, as they say.
Excuse the crudeness of the set-up but I've removed the over-centre spring from the point just off Low Shott viaduct so the blades are now loose and free. Using the operating linkage, which I previously installed with the car central locking motor, to connect to the point tie-bar, a rubber band looped around the trailing end and a rounded file passed through the opposite end of the band, there is now sufficient tension to keep the points in the normal position of travel from the viaduct. The plastic box houses the auto frog module for powering the live frog.
While holding the file in position so that it doesn't move and using one of my lightest wagons, an empty HEA, I can run through the points without the wagon riding up onto the rails and once through, the point blades return to the normal position. It works, but there is a fine limit to reliable operation with the lightest wagons. I will have to do some testing with wagon weights in order find the optimum weight per axle for my needs.
I haven't yet sourced a suitable spring but there's no reason why the rubber band or a piece of elastic wouldn't suffice for the time being providing there's a means to adjust the tension. Obviously the points will need to be kept clear of dust and debris but that applies equally to points that are motorised.