I have the Avtex Garmin 660 with a caravan mode. It's expensive but I like the large screen and the amount of info shown on the screen.
We toured Ireland and France this year and it always got us to where we wanted to be. I also fitted a camera on the back of the Shogun and when reverse gear is selected the Garmin picks up the picture automatically.
We recently got the Garmin Camper 760LMT-D 7-inch ... expensive (though cheaper than the 2017 update, which may not be worth the extra) ... but it beats the pants off the 'on board' 2017 VW product in the car .... shame that it can't be read on the in-car unit ... but a great 7 inch screen ... haven't had it long enough to really assess how good the change between car/van/lorry is, and what difference that makes.
In the three weeks I used it, this summer, it didn't try to send me down any narrow lanes or silly short cuts ... when we've done a couple of months with it ... which won't be till next summer ... then I'll know whether it was a good investment ... or not!
Even as a standard satnav (when switched from towing to car mode) it's far better than anything I've previously used ... the exit and lanes info when on complex motorway scenarios is excellent with pictures of the exact signage shown alongside maps.
And the lifetime maps updates is very good too ... makes the overall high cost more affordable when spread over the putative lifespan.
You can also plug in various camera units for reversing etc ... haven't got those.
There is a rather strange anomaly: It comes with a full set of ALL EUROPE maps ... however, the on board memory is insufficient to download the lot ... you can, if you need to, change countries at a later date, should your holiday needs require that ... we currently work with what would have been a 'WESTERN EUROPE' selection of countries.