I'm not sure of construction details on your 8' x 8' table, but I'm presuming from the discussion on this thread thus far that the rtrack isn't nailed down yet. If that is correct, cut the table in half to make 2 4' x 8' tables. If you haven't used some 1" x 4" perimeter framing around the table, do it around both of the tables you get from cutting it in half. I'm also presuming that you are planning for a "what if" move situation before going farther rather than a layout to be moved on a regular basis like in modular railroading. If that is the case, repeatable alignment is probably not a big problem. Door hinges with removeable pins would certainly work for alignment first time every time, but drilling holes through the two frames adjacent to each other and bolting it together with nuts. bolts, & washers would certainly work. I think the Lionel modular clubs bring their rails flush with the end of the modules, and install the Lionel track pins on one side, then carefully line up the next table to put those pins into the rails on the next table. Once the pins are in place, the tables can then be joined together with a clamping device and track alignment is good.
Some other things to think about before you get farther along in the building process are the type of scenery you want to put on the layout and how permanent it will be verses removeable scenery. Also what sort of access will you have going in and out of the existing room, and how much portability do you want to provide in the event of a future move? For instance if the entry into the room is a hallway that goes 90 degrees from the doorway, will you have room to turn an 8 foot long table? It may work in this house, but how about any possible future house? A four foot wide table will have to turn on its side to get through most standard doorways. Do you want to put some mountains or other permanent scenery on it that would possibly make it difficult to get it out the door?
What I'm getting at is this. If you cut that 8' x 8' table into 4 2' x4' tables and 2 2' x 2' tables, you can then set them up with 2 2' x 4' tables on each side to make 2 parrallel 8' sides connected by the 2' x 2' tables on each end with the center left open. You will have room for the same layout you are currently running. You don't need the center part of the table because you can't reach it anyway; but when you move, the whole thing will be very protable.
welcome to the gauge