the rear seat can be removed , If you are a big guy , I do not think you can fit through it ,, but remove the rear bottom seat cushion first ,, by pushing on the front edge of it rearward and up ,, do this on both sides,, then it will come out ,, then the rear seat back had two bolts on it ,,remove them and lift up and out ---------but be fore you do this do you have a remote trunk release on the dash ,, does it work ,, do you wont to hot wire it ?
left of the steering column , on the dash
when you put the key in does it turn ,,,sometimes if you put your wiegth on the trunk lid ,, down ,, and put the key in and try to turn it at the same time ,, the trunk may pop open ,, other than that ,,, got any kids you can put through the rear seat ?? in the 80s some rug rat locked them selfs in the trunk ,, so Ford put these glow in the dark handles in the trunk so if a kid got locked in they can pull on it and open the trunk ...if no kids ,, then yes a locksmith
look above I wrote more