I typically use the built in Apple maps which usually works well, however, it is not always friendly for towing TT's.
What I am looking for is the best (iPhone) app that I can use to manually select the route that I would like to go. For example, type in the destination and then be able to adjust the route by selecting other roads that are more suitable for towing an TT.
Sometimes campground websites say to avoid GPS directions and to use a different route that they list out. I am not aware of any way that you can do this with the Apple Maps or Google Maps apps.
Good luck ... i have a rand mcnally for rvs and it will allow you to put in length,hight and width of your unit and then look for routes that allow that size .... i have been in bad situations where hight was a problem and it can get ugly at times
I really like this so to plan but it doesn't help with things like low clearance etc. I use Allstays for that. It does allow me to plan a route and tells me distance and time as well as info on the route like elevation changes and curving as of the route.