If you have to go, just turn up late. Ten minutes before it ends is even better with just enough time to use the bathroom.
You know, had to work late, traffic problems...at least you made the effort to be there...what do the complainers want...that you don't come at all...
Else you can get a migraine at convenient times...
If a tablet is frowned on, just print a bunch of interesting stuff to read, making sure one or two pages are wt library printouts of something on that week which you can flash when people look in your direction
And as Dazed said, choose your seating wisely
I've seen people sit through meetings with earphones in their ears the whole time. If you sit against the wall you could entertain at least one ear this way...
For service, if you have do it, make sure you turn up just after everyone left so you can say you went out and just had to work on your own...we all know how that goes...