Wondered whether anyone has any experience with products designed to protect windshields from rock cracks? My windshield is perfect & would like to keep it that way. Have several 400+ mi road trips planned & rock damage scares the living daylights out of me. Never have thought guys who replace/repair windshields can ever equal factory windshield installation & sealing, as a general proposition.

 

Well, here in Australia the following is the typically used windscreen-rock-protection for the outback:

But I dare say that this design is not easy to find as Jaguar accessory...

When I read your question I immediately thought that the principle of how screens of mobile phones are being protected by an overlay plastic sheet should work as well on a windscreen. And indeed, those film are being offered for sale. - At second thought, those mobile phone protectors might be more glass (tempered glass) then plastic - and I expect the film for windscreen to be plastic...

While I have not tried that product, I am an engineer and I would expect this film to definitely help.
If I had the mad idea to drive thru the Australian Outback in a Jag (well, I would use an AWD X-Type (since my collection does not and will not include Tata-Jags (there they offer a 4WD))) I would definitely place this film over my windscreen for this occasion.

Long term I would expect possible issues with this film - like peeling off at the edges and dirt ingress from the edges and possibly UV-degradation like getting poriferous and yellowish.

 

I doubt the film would last long with wipers scraping across it. Perhaps you could get multilayered film like motorcycle visor tear-offs. Just peel a layer off when it gets too scratched.

 

or, get a hybrid rental with full insurance.

 

Rocks just don’t fly up and hit windshields on their own. Something flings them up. My best response will be to create an increase following distance.