Phonegap with node.js for cross devices

We developed a mobile website using HTML5,jquery-mobile,JS(Knockout.js) as front end and MVC4.net as back end and also i am using App Fabric for distributed caching, all my views are .cshtml files everything is working properly across multiple devices as web app now my customer has asked for a feature(file upload) which requires my application to have a bridge framework(like Phonegap) , but my concern is as we have used MVC4.net as backend,.cshtml as views and also App Fabric i have to remove these components and start from scratch. I agree changing the .cshtml to .html wont be much of an issue but my backend will change drastically. Customer is ready to compromise on timeline but he is very much particular on this option.

Please let me know whether my understanding is correct? I am planning to make all .cshtml files to .html files and use Node.js as backend server. Is there any issue with this approach? Does Node.js supports Phonegap?? And is there any better option to achieve the same.

With Best Regards, Sajesh Nambiar