Many years ago I tried to do my own fittings and I have the tool and can change the pedals, was planning on doing it but saddle height may be off. I don't know how much difference in height there is between SPD's and Frogs.

If I don't find a PT before my ride I will have my fitter tweek the fit.

Will riding the mtn bike more before this tour help my body adjust to it? I primarily ride and train on my road bike and plan to do most of my training for the 3 days on my road bike. I'm not talking mtn bike trails but riding on the street or gravel trails.