Bongo Fury

I decided to fit EGR blanking plates to my diesel Bongo, but was unable to remove the rear bolts, the ones firmly rusted in to the cast iron exhaust manifold. The forward bolts into the alloy inlet manifold came out easily. My question, I know the plates come in pairs but would it be ok just to blank the inlet end or will this have some detrimental effect on the vehicle, or at over twenty years of age should I leave well alone?

Blanking the front one is ok if there's no egr fumes in the cab or lots of soot around the egr and bottom of the drivers seat.
If not, a good 3/8 rachet with a 12ml 6 point socket should undo the bolt.