Our standard system is a raid 5 array for a local server.  On Site backup is through Veritas System recovery.  Off Site backup is handled by DATTO and through image backup to Citrix ShareFile.  ShareFile is an encrypted storage platform with unlimited storage and easy access for sharing documents.  We retain a backup server for redundancy on site and can transfer virtual drives as need should a situation arise.  I realize virtual machines are not supported by Intuit for ProSeries but as an IT person I have had zero issues with them over the years.  For VPN access we utilize an encrypted Cisco_Meraki VPN which allows us to implement RDP inside the tunnel so RDP is not exposed.  This allows the user of the VPN to have extremely fast access and not experience the standard sluggishness of the remote database.