It would have been easy to put laminate on the backside a few days ago, but now I have holes for locating pins and screwheads for magnetic holders on the backside.
2-3 days after applying the laminate, the backside of the one cover is still dead flat. The other cover has some bend on one corner, where the material is thin, but it had that after roughing out. I have that piece fixtured with some weight on that corner, to overbend it, to see if I can convince it to go back to where I wanted it.