Unless the freelancers are blowing through a symmetrical 10GbE pipe as well (that is peered perfectly to arrive with low enough latency) …that plan will not work…also your VPN hardware on both sides need to support these speeds as well …you will not be doing that with port forwards (a criminals dream…ransom)
I am not an expert on shared video editing …but @Bob does this for a living (was it using proxy files?)
With 4 spinning disks, you will never reach 10GbE speeds, even on RAID0 and sequential reads.
If you use a shared network, talk to the admin on site how exactly this is setup…but one thing is certain, you are looking at a NAT situation and not public IPs, so exposure to WAN is not a danger)
You should still setup a local router to keep anyone in your location LAN from snooping around your NAS.