I’ve just realised I missed something in this.
Why not put the camera straight on to the main telescope, display the image it generates, platesolve via a cygwin installation of Astrometry.net and have the software tell you how far to move in RA and Dec to get to the right place. Most Astrometry.net solutions only take 10secs on my 5 year old laptop, so you could point at the rough location and be there 2-3 minutes later.
If you are not autoguiding why have the finder guidescope at all? Eyeballing along the tube would give a good start point.