Bill, I think that it would be worth the investment in auxiliary VF. The 35 mm lens is a "people" lens & you don't want to be cutting people out of your picture because you lack parallax correction. With practice, you can get to the point where you can do a good job estimating. In such cases when precise framing isn't important, it will be easier to estimate so that you can focus& compose in the same window. However, when more precise framing is important, you will need a 35 mm viewfinder. I would look for a Voigtlander accessory VF - much cheaper than Leica.
Your other option would be to replace the Voigtlander lens with one of the older Leica 35 mm lenses with "eyes." These lenses were built for the M3 & came with an attached spectacle viewfinder. When looking through the camera's parallax corrected 50 mm viewfinder, your view is directed through these spectacles & it becomes a 35 mm view.