Brainx128,
Good call, walk away, cooler heads prevail. We all have been down this pain funnel that ends up in frustration and at times making things worse before we make them better. You will feel better tomorrow for sure and you will succeed.
You got screwed by a really bad case of rust, or this would be done tonight. Know if you took it to a mechanic they would be charging you $125.00-150.00 an hour to break this loose for you. (And maybe break it and charge you for the part too!) Then another 6 hours to do the actual work. So you will save $800 -$1,000 dollars, your just having to work a little harder for that money than you thought!
Food for thought -
1) I was going to say it might be easier to pull the ball joints and take the steering knuckle with it. However from the pic they are rusted up too.
2) Did you use the air hammer from the back? (Don't use the chisel bit, rather a flat punch bit. (Auto parts store, Sears, likely Home Depot if you need one, most are universal.) Suggest pushing the plate out of the steering knuckle from the back side (Engine side) VS trying to pry off the front.) Careful not to mushroom the edges together, hit 1/2' from the edge of the spindle plate. My guess it its not very stuck plate to plate, its the steering knuckle center hole that is rusted onto the back of the spindle plate circle. (As I recall they are machined to fit inside of each other and thus center inside of each other for alignment reasons.) So that rust has a hold on it and vibration and oil will break the rust bond and free it up.
3) I would soak it every hour (Front and back) with penetrating oil till you go to bed. Maybe heat up the back side of the knuckle, then spray on more penetrating oil yet tonight.
4) Heat is your friend, but heat the steering knuckle, not the front spindle plate. Heating the spindle plate will make it expand in the hole and get even tighter. When hot the oil seems to seep in deeper.
5) I really like Double S Diesels spindle socket suggestion from Amazon with a slide hammer as your back up plan. That would give some good pull torque and some great vibration.
6) Remember now is the time to do wheel bearings, rotor, and brakes if anything is showing signs of wear. VS having to pull all this work back apart in 6-12 months.
If all this does not work to free it, remember time is money and money is time. So it will be time to bite the bullet and get both parts used out of a junk yard. They can take them off together by simply removing/cutting the ball joints at the junk yard.
Lastely I suggest you do the other side too. (I know that is probably the last thing on your mind!) However imagine you are 5-10 hours away and the other side gives up. You (Or your truck) will be stuck for a couple of days while some poor mechanic goes through the same pain funnel to find out its rusted up and he needs to order parts that are a day, two, or three out. Then sends you a giant bill.
Stay the course you can do this and you will make it happen!