For those of you interested in duplicating the signs, here is the receipt:

Buy one 4'x4' x3/8" plywood sheet ($7.79) and have it cut in half. Now you have the material for two signs that can be transported in any truck or van and some trunks.
Buy four 1"x3"x8' legs ($1.69 each) for each sign. Connect a pair of legs at one end with a hinge ($1.49 each). Install two 1/4" blind bolts ($.69 for four) 6" from the top (allows room for long hinge) and 3' apart in one leg of the pair (drill 5/16" hole through and hammer into side opposite sign). Drill 5/16" holes through the other end of the A-frame legs. Cut 1/4" rope into 3' lengths. Tie a knot in one end. Thread the rope through the leg holes. Tie a knot in the other end. The rope keeps the legs from spreading too far apart. Adjusting the knot position adjusts the support height to accommodate uneven terrain. The rope can be thread through weights or weights can be laid on the rope to resist wind.

Drill four 5/15" holes through the 4'x4' x3/8" plywood signs 6" equidistant from the corners, so you won't have to worry about sign orientation for assembly. At the site, secure the signs to their A-frame supports with 1" or longer thumb screws with washers on them to protect the sign.

Paint one side of the plywood white so nothing shows through a paper sign placed on it. Use a graphics program to create the sign on 24 sheets of standard paper and standard orientation (6 across and 4 down). Select maximum printable area and print on laser printer or equivalent. Remove border where it obscures text or graphics and glue stick together and secure with tape. Use spray glue in an open area in the middle of nowhere to secure the paper sign to the plywood. Alternately use spray glue to adhere each sheet to the plywood and skip the glue stick and tape. Use spray glue to adhere plastic wrap to the sign or use other method to protect the paper from moisture.

Alternately, buy 4'x8' shower paneling ($11.97) instead of plywood. It has a bright white glossy finish on masonite that is the same as that on dry erase boards. It eliminates the paint step and is a great surface for vinyl lettering and graphics. Leave it blank and buy a lot of dry erase markers if you want a general purpose sign.