The insulation would likely be some type of spray-on foam over aluminum tanks, so not a lot of weight penalty there. Cooling likely wouldn't be done, I assume

The insulation would likely be some type of spray-on foam over aluminum tanks, so not a lot of weight penalty there. Cooling likely wouldn't be done, I assume any excess hydrogen boil-off that couldn't be burned immediately would be allowed to escape through an overpressure vent. (So ideally top it up right before taking off. There could still be a problem if the plane needs to queue a very long time for a congested runway.)