Thanks for the replies. As Monte suggests a mid sized coil would probably work best, just like it does in parks. The Magic 5x8 works great on the Teknetics Delta 4000 I use for quick park hunts, so I will put that on the F5 and I have a Cors Fortune 9.5x5.5 DD coil I will bring also--just in case.
I have the Nel Sharpshooter coil I bought in the correct frequency to match my F5...I believe it is the same as your Fortune coil.
In my trash and iron infested sites it is shockingly and extremely effective, much more than anything else I have tried.
Deeper, quieter, much more stable in higher settings, deals with heavy EMI and masking situations insanely well.
Then again the 3 other DD's I tried were not matched in frequency which I believe matters...a lot.
Maybe not so much on other models/brands here and there but on the F5 matching frequencies seems important...in my experience.
In my case most of them were lacking, a waste of time compared to the Nel.
I have 2 concentrics that came with the F5, also, they work pretty good but in my mineralized soil again, not even close to the Nel.
For me the Sharpshooter is THE coil of choice.
Everywhere I hunt, anyway, including and especially in trashed out old home sites as you described.
If your Fortune coil is a match I would be using that, if it isn't but that Magic coil is in my mind that would be the better option.
Masking can be a major issue at old home sites and smaller coils deal with it all better and ultimately will notice and find more than bigger coils.
Again..they always have for me.