Standard roses are grafted - in fact, they are double grafted. Typically there will be a rootstock that is grafted to a clear stem or trunk, then a top graft with the featured rose on top. This double grafting - specifically the top graft - is typically what makes standard roses less hardy than a single graft or own-root roses. In your climate, even commercially grown standard roses would have a tough time in winter and most likely should be brought under protection.

I guess you could try the method you propose and see what happens but I'd be very uncertain about your chances for success in creating a well-formed, viable standard.