My last marathon was virtual, at the end of March. However, the event coordinators cancelled just days before the event. Since I had done the training, I decided to run mine the same day. So I was just scrambling to find a suitable location that would allow for adequate hydration.
I picked a local lake trail with a 6+ mile loop and ran 4+ laps, until I hit the full marathon distance. A friend ran it with me. I knew he was faster and he was just running it for support. We parked our vehicles on different sides of the lake and backed up to the trail, with water bottles in our trunks. It wasn’t ideal, but it worked.
As far as my goal, this was only my second marathon and the first was a disaster (dehydration, severe cramping, etc.). From my training, I had a pretty good idea of what I was capable of. At least I knew what my sustainable marathon effort felt like. For whatever reason, what felt like a sustainable effort was 16 seconds per mile slower than it was in training. Maybe it was because I trained alone and talking was making it harder. Or it could have been the strong headwind, pouring rain, varied terrain (some concrete, some asphalt, and some unpaved). Regardless, I adjusted and ran what felt right. I finished strong, but feeling like I couldn’t have run it any faster.
Anyway, if I knew an upcoming race would be virtual, I would practice in the same conditions as race day. Either train and race with somebody, or train and race alone. Also, I would put in a lot of time running at the virtual race location. I hope this helps in some way.