Thanks Jrm223 for very thorough and decent answer sounds like a nice van you have there.
Yeah in my situation it's not a case of miles but more a matter of metres before I'm fidgeting and about going crazy. As I said I have all the adjustments going on it height, recline, lumbar etc..but non of them achieve a comfortable seat!
Haha yeah and got no chance of taping a sat nav on the windscreen whilst driving, unless you have 2 metre arms!
The seat cushion you own sounds interesting but does it do anything for your back or is it solely for arse comfort? As you say there is a fair bit on Amazon.
Tempted to take my work boot to it to soften it up and relieve some stress at same time ? but don't think my boss will be too happy!