Nothing is impossible but...
First of all, if you switch the thermostats so you get 180 degrees, you will need to take both of them out if the 18 because the hi limit thermostat(87) will be set to a higher temp than in the 19. If you don't, you will have the 19 tripping the hi limit and shutting down the whole machine.
Also, you have to realize that once you go over the 150, then any protein based foods left on your dishes will likely cook right back on to the dishes and you may have some problems with washing results. But then again, you are only heating a small amount of water and it cools down as soon as it get pumped around the colder tank and dishware so maybe not such a big deal. Just be ready for longer warmup times and longer delay for the final rinse. Remember. it heats the final rinse up in all complete wash and dry cycles. You should get somewhat better drying with the dishes at 180 instead of 150.
If you want to experiment, have at it at your own risk.