Experiences with toll boxes for over 3.5 tons

Having been in quite a few countries on our current trip we have had varying experiences with tolls  with our 3.85 ton motorhome - some more pleasant then others!  Austria, despite all the scary stories wasn't too bad - a very nice man at the German service station near the Austrian border, helped us calculate how much we'd need to put on the box and the deposit was a very small 5 Euros.  The only problem we had was returning it as we took the tunnel to Slovenia and didn't realise that we had to return it BEFORE we went through the tunnel!  In Slovenia we tried to be honest and pay at the larger vehicle toll booths - we could have probably not bothered as each toll booth girl looked puzzled!  In Slovakia the girl in the Shell station rang up to check and decided we didn't need a box, especially as their roads were so awful (they were!). Apart from taking a little time to find a collection point, the Czech republic was fairly easy.   Poland was the worse country - first trying to pinpoint where to buy a box, then paying for it as the girl was  in a bit of a tizz, then returning it - on the motorway at the border the ViaToll office was on the other carriageway so we had to go into Germany and back into Poland to hand it in and retrieve our money! It was worth it though as the deposit was £25!  Hungary were very switched on - we paid beforehand on the internet - a week's toll which also included a weekend, giving 9 days. 

We did notice that large foreign motorhomes didn't seem to have the boxes on their windows - were we TOO honest?!  What have other members found on their travels?