For steady state cruising the pusher trailer is more efficient ... but a generator trailer have other utility abilities to it that a pusher trailer does not ... power outages and such... and as speed changes to that which is outside the efficiency band of the pusher trailer ... the generator might be more efficient in those other conditions.
If I was going for a generator ... I like what AC propulsion did for the T-Zero.
20kw continuous ... all together the whole trailer came in at 300 lbs ... had a 9.5 gallon tank ... and they claimed to have a tank to battery efficiency of 22% ... which isn't great ... but it isn't horribly bad either ... compared to the 25% to 30% that most straight ICE cars get... and as was posted it would still have the EV range for shorter trips.
And a little 20kw generator like that should be able to handle an entire house load during a black out.
