The easiest way I ever found to do this reliably, is to configure OpenVPN to distribute similar IPs to the clients. For instance, if your home network range is 192.168.0.1, then configure the OpenVPN server to distribute IPs in the 192.168.1.1 range. Ive only done it this way because I have a rather large home network and lots of devices pulling IPs, I dont see why you couldnt dedicate OpenVPN to give IPs in your subnet though, say above .245 or something. Then once a client is connected they should be able to go to smb://192.168.X.X/share or use //192.168.X.X/share from a Windows box. The shares *should be visible. Then its a matter of allowing guests to the share via the permissions of the dataset/share..