There was a problem uploading my file. :/ Basically they're pretty white with a sort of hot red glow around them. I have them just outside the tent now. The bucket is emitting a fair bit of heat, is that likely to be a problem? I'll put it on a heat mat but I mean in terms of melting the tent...
sanctioned-suicide.net
This post advises that it's important to let the charcoal cool down a while, before taking it inside. The article the poster linked is about a woman who accidentally died by taking a completely cool bbq into a tent, 5 hours after it was lit. The man survived after 2 weeks in intensive care. Therefore, waiting 5 hours is probably not optimal, but waiting 2 hours sounds ideal.
Zanexx succeeded by waiting 90 minutes after tipping out of chimney starter, which it was probably in for about 30 minutes, therefore, overall it was taken into the tent about 2 hours after first being lit.
According to the above poster, not only does waiting 2+ hours, reduce the fire risk, but this is also the time of optimal CO production. It will still be hot after 2 hours, so you will need some heat resistant surface to put it on. I think Zanexx used mats for putting curling tongs on.