Harry
I have a zetec conversion with the turbo upgrade. Part of the package was a dash daq. It looks just like a larger gps unit but data logs,shows all sensors with digital gauges,bar graphs,dials,etc..it is very nice and I love being able to log every drive. I have about a years worth of driving on one little sd card. The downside is that I worry all the time about it being stolen. It's has two multi pin connectors that are on the back and repeated unplugging has slowly made the connectors loose over time. If I could only find a better place to mount it more hidden from a passerby view but still visible to the driver. I do love all the information it gives and the ability to program high/low alarms for all inputs. 
There are similar devices on the market that do the same thing for various prices. I think your idea of using a blue tooth adapter is what some of the "tuners" do. I seen a Wrx that the owner mounted a tablet into the dash that was fed via blue tooth. Using the touch screen he could choose what ever type of display he wanted. 
What ever you do pick be sure to check with Bostig when setting it up. If you choose a setting for a sensor that we dont have the computer will assign a default value that will throw off the rest of the readings. Just a few things for you to consider while doing your researc

Bill M
87 Westy
Zetec Turbo