I will use TCD0 in split mode, to have two 8 bit timers.
I want to generate an event from one of these on underflow, which is said to be supported in the manual.
But when I look for the particular event source for CHnMUX, I don't see anything specific for the Type 2 timers. There should be two event sources listed, one for the low timer and one for the high timer.
I'll try experimenting with TCD0 as event source to see what happens...