Rear quarter body help needed

Working on my 66 Dart and as many know there are no complete quarters being repopped. The only thing available are patch panels. So I bought the wheel house panel and the lower rear panel. The method that we used was to glue them on to the body using the 3m 8115 bonding.
Once the 8115 was spread and the parts bonded together we used small sheet metal screws to pull it all together and tight. I left those in place for at least a month as I worked on other things. I removed the screws and tonight I welded the holes shut using an air hose to immediately cool the welds down. Here is where it looked like once welded and also you will see where the belt strip holes are welded shut as well.
DSCN0499.JPG DSCN0498.JPG DSCN0497.JPG DSCN0501.JPG DSCN0500.JPG So I guess its time to try to make this smooth looking and original.
Im moving forward on this on my own as the body guy that owes me money hasnt shown up in months to finish paying off his debt.
Heres my plan and feel free to throw ideas at me to move forward. I was going to use a thin layer of short strand fiber glass filler as the base. Once sanding it down go to standard filler. Now Im not the best at spreading filler and I dont seem to be able to get the filler as thin as I see them spreading it on TV. Ive been using evercoat rage 106. I have a reducer that Ive tried using that is called honey, not sure what the real name is but its supposed to thin the filler and it works but I didnt know how much i could use.
If you were doing this rear quarter work, once you got to this point how would you attack this? I think I will try to do what I have read about by trying a skim coat from the top body line above the gas cap down the entire quarter? Is this a good way to start?
Im no body guy so i need some guidance on how to move forward.
Thanks Rod