combo of ISL remote desktop through either AVAST cloud care or barracuda managed workplace and mesh central for a backup solution if those are down for some reason.
ISL is free for us via both cloud care and managed workplace. Mesh central is also free.
Most Professional support solutions allow the client application to be elevated to admin. Often even by pushing the admin credentials by you. Here is a good example that also allows for using a private connection server. https://www.islonline.com/nl/en/
Couldn't be happier with ISL Online. Can't talk about their Cloud solution as we are using self hosted. We had zero problems in the last three years. We patch it regularly and we bought a few additional licenses for more concurrent connections but other than that was set and forget.