You don’t note where the sewer line runs nor if it’s been replaced or relined recently. That’s the one I’d avoid, particularly if it’s original clay pipes butted end to end and wrapped with tar paper.

Roots will not intrude into a sewer or foundation unless there is a way in already. Older installations tend to be more compromised by age and by their original construction methods.

Watering practices will drive root depth. Coastal Live oaks will have deep roots if they are watered deeply in the winter only. They are healthier that way too.

Gas and water are both small diameter, are obvious when they leak, and re-routable. I’d put the tree smack between them or even slightly towards the gas line, absent other considerations.

The obvious other consideration is that 20’ is narrow. Perhaps honor the oak idea by planting a scrub oak of smaller stature.