Nothing works better and costs less than going out for a moderate ride and seeing how it goes.
Repeat often, looking at what works and what doesn't and adjust. It also serves as a training regime to htfu a bit.
I consider myself lucky that I commute daily and ride most weekends so that I am very familiar with how my touring bike performs and how I fit on it. I couldn't imagine buying or building a ride and worrying about performance without a good breaking in period first.

Those who tour for a while generally find a sweet spot that works for them but also get to see other people touring successfully but differently. That diverse exposure helps to keep opinions true for themselves but humble enough to avoid absolutism. Pedals are just one of those things.