I took my OEM seat into Terry, a local guy here that comes out to bike night.
My seat was in about 95% good condition until it sat out in a couple of 5 minute hail storms that completely destroyed the vinyl cover.
Terry has at least 20 years or so experience in custom upholstery in classic cars, trucks, boats, motorcycles and home interior furniture. He just recovered my seat, no modifications to the padding, and my cost last summer was $235 CAN. The new marine grade vinyl is about 5 times the thickness of Ma Kaw's original stuff. The newly covered seat is much more comfortable now.
Robert, I am a big guy too, not so tall at 5' 10.5", but relatively heavy at ~270 lb currently. (Down 30 lb from when I started riding again 3 years ago.)
I have not tried any of the aftermarket cushions myself, but have been thinking about the Buttbuffer:
You will want to order the large size 18" X14" to fit the vn750 seat.
(BTW, the seat pad shown in the link you posted is too small for the mc driver.
It's 10.5" X 11" size is suggested for the pillon passenger.
There are 2 different Airhawk pads I believe, that have a good reputation as well.