In fact... why not just throw the Silpat into the oven on a cookie sheet and bring it up to your extrusion tip temperature (+50 degrees, say) right before the start of your print job. You'd then transport the hot Silpat over to the bed, run the z-adjustment and start the job. Since the Silpat is about the same temperature now as the hot ABS, it may then adhere nicely like this. You could do a spot-check for temperature of the Silpat, determine that it's now cooled to the extrusion tip temperature and you're ready to start the job.
Or put a pizza stone into the oven, bring it to temperature and then print directly onto that?