Hi Motivator -
Not sure taking any more foam out of the seat is a good idea (comfort wise), but I'm sure someone could reshape it for you?
There is also a German company: Off-The-Road.de that produce lowering links (-35mm) for the rear and you can drop the forks though the yokes (the bike has quite high bar risers so there is plenty of room), which should see the height much more manageable?
If you have a few more £££s (or technically Euros of course), they also offer a full lowering kit with shorter shock, fork springs and linkage that drops the seat height to a lowly 835mm (that's 85mm lower than standard):
It's a great bike, whatever height you chose to ride it!
ps. check out XT660.com for lots more info on the new Tenere and the other XT660 machines...