If you are able to move the settings from the web.config to the ServiceConfiguration.*.cscfg
(e.g. Cloud, Local) then you are able to add additional versions of these files, such as ServiceConfiguration.Staging.cscfg
.
During deployment (both via the IDE and via Powershell) you can specify which configuration to deploy.
In my case, I use ServiceConfiguration.Cloud.cscfg
for the Production slot, and ServiceConfiguration.Staging.cscfg
for the Staging slot.