I see no reason why not, try it and see
I would be happy to help out if you need assistance
You have full SSH access to the server so just update the betas section in steam settings
Edit - This does not look to be possible server side. In that case im not sure how you downgrade a server install.
Ahead of the a19 launch to experimental i have a hosted server which is currently not on the experimental branch,
Does anyone know the process of switching this for a hosted nitrado server?