Sat Nav

First year with our Motorhome and loving it. The only stress we have is in journeys and trying to avoid sharp corners and narrow roads. We have thought about buying a Sat Nav specifically for motorhome / caravans but are seeing mixed reviews. 
We tried downloading CoPilot but it directed us down roads not suitable for over 7.5 tonne. As my husband said, technically passable for our Motorhome but do we need the stress of it,

I looked at reviews Of Aguri Sat Nav and Tom Toms and both say they have the same flaws - i.e. take you down very narrow lanes. 

Can anyone provide some recommendations.