It may not be an issue for you, but our HOA ended up not adding entrance cameras at the advice of the HOA lawyer. I'm not a lawyer, but the gist of it was that it created additional liability for the HOA that didn't exist without the cameras. I argued for them due to constant damage to the gates, but they got scared. There was also some issue with video in a public area. If you have an HOA I might recommend bouncing it off the attorney.
Others on here would probably know better or have more detailed advice.
Many manufacturers have pole mounts for dome cameras. Its going to depend on how high you want or need cameras on what type of mount you get. I've seen ones that can mount on the side of a metal pole and some mount on the top.
You will find that any tall pole is going to have to come from a local yard. Metal or Wood. Wood will probably be more cost effective, but we don't know where you are located.
Check your city ordinances or local laws for height and location.