In lieu of oleanders, you may want to consider wax myrtles. They're evergreen and can be kept as a rather large shrub or limbed up as a small tree. The leaves have a bayberry scent when crushed. They do drop smallish leaves but near an equipment pad I don't think it would be a problem. We have 2 that are growing as large shrubs (about 6x8) here in north TX and also had a couple limbed up as trees to shelter/shade an a/c unit when we lived in NC.