One idea for dealing with an ASI failure is to know the RPM of the engine at gliding speed with the engine at idle. I think on the Bulldog it's 1300RPM.
If the ASI fails, fly at high power setting (ie fast) to the overhead, and then fly a PFL pattern at idle using the RPM to confirm speed.
I've tried it on a couple of aircraft and it's surprisingly sensitive on both VP and CP props. Worth considering anyway.