fine grained canvas or wood

Hi there, I am a painter from Sweden, temporarily living in Denmark. I hope I am not getting banned for posting almost the same thing in two different sections but this is a question that might be adressed to those . who work in acrylic as much as those who paint in oil. As for myself, I am an oil painter. My question concerns the actual painting surface. I am about to take the next step from naturalism to hyperrealism, and am struggling a bit with the issue on which material to use to paint on. I plan to use large formats, 110 x 130 cm or like 110 x 140 cm. Now, in extreme realism you either need canvases with VERY fine grain, or some sort of surface with no grain at all - preferably totally smooth. And the large format doesn't help. In Scandinavia very fine-grained canvases are hard to get, and if you do, they cost a fortune. besides, I would prefer the totally smooth, and flat surface. Some kind of board would be better, but the gesso boards you see in England and USA can't be found here in Scandinavia, and their sizes are too small. One alternative could be a wooden surface, grounded with gesso, like plywood. Because of the large format, it has to be a light-weight wood. I know that some Italian superrealists, for example, uses poplar plywood because it is even lighter than any other plywood material, but again - very difficult to get here in Scandinavia. And do you need to support a wooden surface on the back, with frames or beams so that the material doesn't warp? Do anyone here have a suggestion of what I should do? Superrealism is very popular in USA, do anyone know what these guys over there uses for their large scale paintings? Thanks in advance. /Glenn