Mike,
For some of my cars, I have gone the route of the clear adhesive film bra, such as Invisible Mask. More difficult to apply but far better than traditional bras to protect the paint. Those bras will inevatibly scratch up your paint as grit and dust gets behind them, and that's assuming you actually have one that fits well and the straps and hook don't fly off further damaging your paint.
I looked and Invisible Mask doesn't have a patttern for E3. The other route is to use temporary adhesive film such as TracWrap. There are others out there. This is what I'm planning on doing for my next long trip with a nice car like the E3.
In driving my 1800 and coupe a few thousand miles on the highways I have found that they are far less prone to stone chips than modern cars, provided you drive smartly to avoid damage: Stay out from behind trucks, follow at a distance, etc. Our cars are taller and present less frontal area of painted surfaces than modernn cars. Not to say it can't happen, but I think I may only have one or two paint chips in all those miles.