There are several different options for evergreen screening trees that are within that size range and that are also low maintenance and deer resistant. Here are a few suggestions:
- Juniperus chinensis - Chinese Juniper - Choose a cultivar that is in the size range that you need.
- Juniperus scopulorum - Rocky Mountain Juniper - There are some nice cultivars that are within the size range that you are looking for.
- Ilex opaca - American Holly - Can grow up to 50' tall but usually grows to 15'-30' under normal landscape conditions. Must have a male and female plant for berry production
- Ilex cornuta 'Burfordii' - Burford Holly, 20'-25' tall
Andre has compiled a list of some good evergreen screening trees but some of these are too tall (or short) for what you want and others are not very deer resistant. I hope this gives you some things to look into.