I wore SPDs and finished mid pack somewhere I think. Results aren’t up yet (aside from the prize winning positions). Mounting and dis-mounting only occured twice per lap and I managed to do both on the move without any practice. Not sure my method was an approved cyclocross mount/dismount but it worked for me.
Dismount: swing right leg over back of bike but keep left foot clipped in until you roll up to the obstacle then unclip and run.
Mount: run with bike on ground and hands on the tops of the bars, and just jump onto the pedals. Start peddling. Clip in when you can.