From my experience with travel bench v1, a 8/4 slab is good enough. I really do not want to do a slab glue up for a 50mm thick or so slab. Problem, I do not have any wood in the wood pile that is thick enough and/or wide enough to make a usable slab.
Adding to that problem I went to bed last night and awoke with either a "cold" or a bad case of allergies, bottom line after a bad night I do not feel like doing anything other than drinking whiskey with some honey and feeling sorry for myself. One problem with that plan, I want to work on the bench once I feel like it and the wood store is closed on Sunday.
What to do other than suck it up Bubba and make the trip. I did, and after going through the stacks at the wood store I couldn't find a single board that would work and almost gave up but I remembered they keep the European Beach inside with the $40 USD a board foot wood. At first glance the Beech stack did not look promising but hidden in back was a 8/4 X 400mm X 2200mm hunk of Beech that is perfect for the slab. Whip out the AmEx, throw it in the bed of the trunk and I have my slab with zero glue up....Life doesn't get better.
It is still whiskey and honey and feeling sorry for myself but at least I have the slab for when I can work on it.