We travel to Austris/Bavaria/Italy every summer and its a pretty relaxed and easy trip. Permits are only required for City centres (We don't need them) and in Austria the Motorway Tag is
not required unless you use the Motorway which in the Tirol/Salzburg areas is basically the one road east to west. (A12/E45). Ehrwald/Zugspitz - Kaprum/Zell am See - Archensee - are all worth a stop. I would recommend going over the Grossglockner we have done it in a 7.5 meter Motorhome with no issues. Some VERY nice suggested campsites:
Camping Brunnen near Fussen (Bavaria)
Zugspitz Resort near German Austria Border (Ehrwald)
Camping Archensee North tyrol
Sportcamp Woferlgut near Kaprun/Zell am See
Caravan Park Sexton near Italy side of Grossglockner pass
There are several campsites on the Lido di Jesolo peninsular East of Venice and at the end there is a very convenient cheap ferry direct to the main dock in Venice.
Have a good trip.
PS: Even the big ones get up to the top...
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