I've been thinking this over for a few days and in short, yes, you could actually do what you want to do. The big question becomes, is the cost of development time to do that worth it to the business? Or is it cheaper for the business to just rename everything at once?
Now part of me thinks you should be able to setup a rewrite rule that allows our-product.aspx to serve up pdetails.aspx. So you get the our-products.aspx in the URL but behind the scenes it is loading pdetails.aspx (so one page is serving two urls).
Then once all of the URLs are converted you should be able to just rename pdetails.aspx to our-product.aspx and remove the rewrite rule.
Hopefully this makes sense.