[ChrisZang]

The thermostat is very easy, the water pump is the hard part:
to get to all of the fasteners which hold the pump into place you need to partially work from under the car and partially from behind the seats through the access panel behind the seats
I agree that to get to some of the remote locations is a b*tch, but it can be done. I tried pretty much every combination of extensions and swivel heads and eventually I could get to all of them. It basically needs a lot of patience.
What helps is that all the fasteners are torqued very low, so you don't need a lot of force to get them off.
About your question: If you're already that far, I'd pull through with it all the way.