The only way they can get the door back open is to root around the side of the door and pull it back with their snout. Easy fix, which is what we do with ours, put a "door frame" that the door closes into. When the door closes it closes into the frame and when they try to get their snout behind the door all they catch is the frame.
I have been using the spring door type for 7-10 years with 100% success. I have sat in my blind and watched pigs go into an already tripped trap by pushing the door open, so to say they wont is false. What I also dont understand is how 22 decent sized hogs fit in a 5x8. Ours are 4x8 which is not much smaller and have had 6 hogs in it and there was standing room only. And the comment about them being spooked by a door slamming. I am pretty sure that a guillotine style door is going to slam too, and once either slams shut what hogs that are currently in the trap are not going anywhere. ONLY difference is when the spooked hogs stop and turn around to see what the noise was and go back to feast there will be no more entering the guillotine door.

the lease is big time flooded so we put the trap out in our back 40 for now. a couple of the neighbors dogs have been cut up and we are thinking that it was hogs. we baited it with beer soaked corn with a strawberry/rasberry jello sprinkle. not wanting it to catch deer, should i put in a header on the door way about 6inches to 1 foot down? the door way is 4 foot tall now. we are planning to build another trap and i guessing saloon type doors would be a double no no. one more question, this trap is 4 foot tall and i see alot of 3 footers, is 3 foot tall enough?

vw's have been a hobby for the last 6 plus years. my son and i built this one and a few others. getting older, i gotten tried of just splashing around in the mud so we decided to build a off road work buggy/truggy(half truck and half buggy) my son did most of the welding, wiring and painting. my son is still setting up tank traps to test the ability of the truggy.

Yes, 3 foot is more then enough. You get a hog taller then that you mine as well give him the keys to the house.
Saloon style doors work fine as well but your design/style is fine, it will work. Build another like you got, you have experience building it, I would just suggest not as tall.

Trap looks great... Run some barbed wire across the opening at about 2 1/2- 3' to keep deer out. A pig will push under the wire.

Nice VW - my first car was a "baja" bug - that dude would fly!