LTS DVR to Offsite NAS Questions

[B and A]

So I currently am running a 32-channel DVR from LTS Security which is like an re-branded Hikvision. I would like the ability to an offsite storage server so that it can be backed up just in case of a fire etc. LTS Security does not have a cloud storage solution and it seems other ones are expensive and a pain to setup. So my thoughts were to use a VPN so that both the DVR and NAS (probably going to run Truenas) have the ability to "talk to one another" and the VPN would be done on a Asus router. I could then link the NAS to DVR and theoretically start recording to the NAS. 

Is there any problems with this approach? Any better ideas?

Here is a pic of the DVR NAS settings page

 

[Huntsman]

The VPN and internet connection would need to be bulletproof and rock steady in order for the footage to be essentially live streamed to the remote NAS. Any slight dropouts and you will run into problems.

 

Suggest the recording to still be done onto local storage.. Then periodically backed up to the remote NAS. Something like cron job and rsync mashup.