Good Afternoon, Wellspokenman,
For a neat, flat look, dry mounting is, indeed, what you're after. In the situation you describe, however, there are some substantial impediments. Posters are typically rather large and would best be mounted in a correspondingly large press. (Dry mounting by sections can be done, but that can be very unsatisfactory; even when done with extreme care and experience, overlapping sections are often obviously visible.) The other alternative is a VERY large press which will be almost prohibitively expensive if new or nearly impossible to find in used condition. Any dry mount press is heavy and awkward enough to make shipping generally impractical. Even a common Seal 210, which will take 16 x 20 prints whole, weighs a lot--enough to make it very difficult for one person to move any significant distance.
I can't offer any comment on alternatives, except to say that you may find something other than dry mounting to be the only practical approach.