This project is going to be darn tough without the proper tools and skills. Making "patch panels" as complicated as we are talking would tax the most of us to out limits. Not knowing the skills of the OP I would STILL say searching for replacement fenders is the most realistic way to go.
As far as adhesives and safety and the "right" way and all, it's nonsense in this particular project under these conditions if you ask me.
On the "safety", cars are being "glued" and riveted together at the factory these days at an increasing rate. We are talking 4 star crash tested luxury cars. It is VERY common to see things like frame members bond riveted to the firewalls!
Here is a little test my son did back in fifth or sixth grade. Nicks science project weld vs bond and bolt. click here
BMW has a factory guideline for splicing the frame rail at the radiator support with a "glued" in backing inside the rail. We are talking the component that the bumper bolts to! The FRAME rail, you bond this backing inside the rail without a single bolt, rivet, or holding it on but he glue!
As Pugsy pointed out to make these panels is going to take some serious skills (but a great smaller learning project). It has to be done before it is bonded, there is no way you could be shaping that metal with it bonded on right there, at least that goes against everything I know about the stuff and it will likely fail if that were done.
I am thinking go on to something else on the car and hunt for fenders. At the very least hunt for someone who will mail you the front portions of the fenders and then bond them on.