Problems of hydrogen boiling off?
Presumably, the fuel consumption with an aircraft like this is pretty constant, except maybe when taking off?
It could be fuelled immediately before take-off, and as long as its fuel consumption when cruising was higher than the natural boil-off rate, there wouldn't *be* much of a problem.
It's not like having a hydrogen-powered car, where having the fuel boil off in under a week would rather be a drawback, if not a bit of a safety issue.