The Zone System is based on using relected light readings to adjust exposure and development to the actual scene brightness range of your subject. If you don't use a spot meter you have to be close to everything you photograph because otherwise your will get bias in your readings. The short answer for me is, 'no.' If you can't get accurate readings, you can't get good Zone values and the whole system is no more precise than just using an incident meter and trying to guess what the Zones are.