I use Copilot Caravan as an app which runs on my iPad Mini (cellular), it's also available on Android. You would need a tablet (or mobile phone) which has either a builtin GPS receiver or will connect to a seperate bluetooth GPS receiver. You specify what your vehicle dimensions are & state your road preferences, then it will avoid low bridges, narrow roads etc when route planning. Like all satnavs, it is only as good as the mapping data it has available but in 4 years use it has not got me into trouble.
Most of the cheaper satnavs don't take into account the dimensions of what you are driving; there are a couple of stand-alone dedicated units that do but they are not cheap. Copilot Caravan for the whole of Europe was around £40 when I bought it & it comes with lifetime updates (including Maps).
Interestingly, when we had a 3,650kg 7m long 3m high FIAT Ducato based motorhome, that had a dedicated FIAT UConnect satnav builtin, but it used the same maps & routing algorithms as the ones fitted in FIAT 500s..... it was rubbish!