The Overlander through much of its run had the same basic plan as that posted by Silver City. The rear bath was found in probably 95%+ of the pre-1974 Overlanders - - the configuration changed from time to time, but the general characteristics remained the same - - a 3/4 tub/shower, Thetford toilet, wash basin, and one or two wardrobe cabinets (one of which usually contained a swing-out medicine cabinet) (post-1961) - - prior to 1961
it seems that a shower stall was more common with a small vanity and toilet that sat up one step on top of the floor mounted balck tank. Then, in the center of the coach you would find the bedroom - - "Center Twin" contained a twin bed on either side with storage below and quite commonly (1960s) you would find two windows above each of the beds (hammock bunks were evidently a rather common option with this setup) - - "Center Double" featured a fold-out sofa on one side of the aisle and a dressing table with more wardrobe cabinets on the other side of the aise. Beyond the bedroom area, you would find the kitchen area, and ahead of that the living room that usually featured a front lounge with free-standing dining table (pre-1966??) or a credenza type folding table that folded up into a wall cabinet (post-1966??).
During the 1970s there were at least a few of the Overlanders built with a center bath, but it did not seem to be a particularly popular model (at least in the Midwest as I have only seen two or three with that configuration). I would be VERY surprised to find any Overlander (as all according to my information would be pre-wide-body) that would have anything either than a rear twin or a rear double arrangement with the center bath.
I have seen pictures of one 1950s Overlander with the rear bedroom (twins with an extra rear door that appeared to be factory), a center bath, and the rather traditional front arrangement with a front lounge followed by the kitchen area - - it had the free-standing table that was common to many of the 1950s and 1960s Overlanders.
While almost nothing is impossible when it comes to Airstreams and the potential for changes to the floorplan to suit a customer's special order, I don't think that I have seen more than one or two Overlanders with a dinette.
Good luck with your search!