Advice for towing through the Swiss alps

No worries, no problems. If you are entering Switzerland at Basel an official will greet you at the border and sell you two vignettes and will show you the best place for them - he might even put them in place for you.   Pay him with a bank card

From there to Italy is motorway without any snaking steep gradients - instead of going over the Alps the motorway goes under via the St Gotthard tunnel (no extra tolls)  and if you are returning the same way your vignettes will still be valid 

It’s a very busy route and there may be traffic delays.  

Good wishes.

As ET says, there will be no eye watering gradients on the motorways. It’s a steady gradient up to the St Gottard tunnel entrance and there well may be delays in entering the tunnel. Traffic is controlled by a series of traffic lights to limit the number of vehicles in the tunnel. Try to avoid going through the tunnel on a Friday. Traffic around and south of Basel is often heavy and there are multiple tunnels. Traffic around Milan will also be busy and where the A4 is still a 2 lane motorway, caravans are not allowed to enter the outside lane in some areas, just keep an eye for the signs. The A4 is a busy motorway but few motorways in Europe are as busy as ours in the UK. On your return journey the Brenner Pass into Austria and then the Fern Pass into Germany is a decent alternative to returning via Switzerland.