@mathanxiety
I've frequently driven 9-12 hour journeys on American Interstates. Not in a HGV but long haul driving is indeed tiring, and even more so with DCs in the back seats.
I have as well but driving a HGV full size moving truck plus a car carrier trailer towed behind it. Similar to the picture below except the picture is a little tiny sized moving van, the one I drove was 28ft long full size one plus the full size 14ft car carrier trailer behind it. Drove that from Ohio to Colorado. But you may not know this, the Interstates in the US have much wider lanes and are not as twisty as U.K. motorways. The slip roads on and off are longer. They also have full size hard shoulders as standard, which many U.K. motorways do not have. In addition, the drainage is better engineered so if you have rain, there’s not big puddles appearing like in the U.K.
I have also driven long distance in a car with DCs in the back…once doing Florida to Maine in a single day when our planned stop in North Carolina went tits up. Checked into the hotel and went to the room to find a cockroach sitting on the bed looking at us and another sitting in the sink. So packed the DCs back in the car and drove well into the night. This was an absolute breeze compared to driving a full size moving truck that had a 14ft car carrier being towed behind it.
Again also driven long distance in the car in the U.K., from Oxford to Stirling Scotland and again Scotland to Cornwall. The U.K. driving was much more tiring and stressful than the US driving.
Driving a car or SUV is far easier and much less stress than an HGV especially one that is also towing another vehicle behind it as well. It affects your turning, your timing, your distance needed to slow or stop, you can’t just switch lanes, you have to plot out a gradual diagonals so the trailer you’re towing doesn’t wobble…if you move to sharply of an angle or too suddenly the trailer can overturn and that then caused the lorry to flip over. You have bigger blind spots. You have to take special measures to not overheat your brakes on a downhill.
DCs in the back of a car also make it easier to drive, not harder imho as you are less likely to get road drone when there’s a person piping up now and then to have a chat with you.
The seating is also very uncomfortable in an HGV which tires you out faster. You’re being vibrated and bounced around…a car is like sitting in an easy chair and the ride is much smoother.