As a fairly regular user of the HLX, I've never personally seen it more than just over half full. Lots of space yes - but concern that they may give it up. I really wonder if it wouldn't be worth a try at making it twice daily (Mon to Fri)and thus more attractive to the business community.
As for the traffic on approach to the airport. Sunday evening has been notoriously pretty bad for several years. Of course, with the present situation it will stretch even further back. One significant contributing factor is the high proportion of Asian families/friends who traditionally come en mass to say their farewells to pax at the airport. It's their strong family culture and I respect it, but it doesn't half increase the congestion.