Q.viburnums
We have lots of deer frequent our property. Are viburnum prone to deer damage?
What can you suggest to fill a space that has partial sun, more shade, may be dry, maybe in the 4 by 4′ size range, in zone 5?

When deer are hungry or thirsty enough they will eat anything. Deer actually get much of the water they need to survive from plant foliage. Neverless, they aren't generally to fond of viburnum and when given other options will choose other plants to eat. This article may help:
https://www.gardeningknowhow.com/plant-problems/pests/deer/deer-resistant-plants.htm