You run the risk of the employer having you escorted from the tenants job site for trespassing. Also the tenant may persue you for harassment as you have no idea what the law requires in issuing a pay or quit notice. Before you make her mad, learn the laws that govern landlord tenant relations. Otherwise you are heading to court as the defendent.
After all the reason you are having to serve the notice is because the tenant has broken the lease and or is a deadbeat not paying. I don't think the law is going to protect someone who is intentionally creating a situation like this.
Serve them at work its the best choice and if you can afford to have someone else do it, like a company that does this as their businessm better yet.