Looking for speciality tool..

If you are going to drill from the underside it is just as easy (or difficult) to completely drill through the bolt.
When you go back in the car, presuming that you haven't already stripped the hex heads, the heads of the bolts on the frozen shafts will snap off.
At that point what is left in the nut will be less resistant to tuning.
You will need the proper size tap and drill bit at this point.
Drill it correctly undersized and most of the remaining bolt will want to unthread itself out.
Use threading oil on the tap, not wd40 and rethread it.
My prefference at this point would be to use stainless allen socket bolts with AN ss flat washers and anti-seize compound.
I don't remember what metric size is originally in there. I believe that I converted to a 5/16" at this point. I don't remember if it was NC or NF.
This all isn't going to happen in a few minutes.
You are in there for a full day to do both sides.
The left handed easyout isn't going to necessarily make it any faster or easier.
As I recall they are already left handed. That would mean that you should be looking for a right handed one.
I wouldn't bother with them. They won't work well in this situation anyway.

JOHNK..... they make straight cut EZ OUTS and can be purchased I think at any tool store SEARS etc. But I agree with Doug drill them out and use US bolts Stainless .. usually the US sizes is just a hair larger and can be drilled and retapped.

Looking for an easy-out for a left hand thread bolt because I would be driving the bolt back up into the cabin, so it would be opposite of a
normal easy-out. A straight cut easy out would work. One seat is locked into position so that the front bolt heads are completely inaccessable from inside the cabin. I'd have to drill a pilot hole in either case, I can drill a shallow pilot and try the easy-out, if it doesn't work, I can continue and drill the bolts completely out. Thanks

It's your choice of poisons. Be advised that ezouts break off in the nut also.
That is a nightmare to get a hardened bolt out of a nut that you need to save. Been there, done that!

I from the school of grind the bolt flush with the nut from underside, and drill pilot hole then just about the size of the the bolt. I belive it to be 8mm X1.5 Worse come to worse you could use a nut on the bottom side.

Not sure how far you have gone, but Snap On has left handed drill bits, that I have used before in some cases with good results.