I laughed out loud reading this whilst I sup my first cuppa....
There was only ever one sensible solution - use a trailer. Attempting to 'max-out' a vehicle and take it on a long trip on public roads is nothing short or stupid and dangerous.
Off to make another cuppa as spilt the last one reading some of the suggestions ....
I don't know where the CWN webpage got that info from ??
As the payload was never listed in the official LR brochures, only cubic capacity, and it's 1500 Litres for the commercial FL1, not 1400 L as stated in the CWN webpage
LOL, I did similar a few years back with a Mondeo. I got 30 old UPS batteries free from work (with permission of course) for a wind turbine project I was building. I brought them home over two trips, no idea how heavy the load was but every time I hit a bump the wheels rubbed on the arches.
Best about it was, when they eventually died I got a tenner each for them from the recycling centre, didn't mention that to the boss tho.