Oh, sure some folks even opt for the square edged plank. But what you have to do is use a good urethane adhesive in long continuous squiggles about every 2" on the back of the plank your are about to lay. Some floor guys use a pneumatic gun to tack it edge-wise in place to hold it while they screw it and peg it. Or else use the cut nails. The same principals apply with the subfloor as I have already mentioned. Just make sure the subfloor is really level and flat. It's a really good idea to undercoat these planks else they will have a great tendency to warp. The is no T&G to stop the warp.
But don't use just any old lumber from your lumber yard, it's air dried, and you will need real kiln dried material (to the average EMC in your area-find out what this is from a carpentry or flooring shop). See if you can find a local mill to do such work. I don't really recomend the new plantation pine and softwoods for flooring. Look for old growth (lots of rings per inch) Eastern White Pine for a light duty but quite appealing floor. You will have to edge plane this yourself, or get a shop to do this.
You should be warned though that when you lack the T&G, when the boards shrink during the heating season, your gaps will be the full depth of the board. When you go to a thicker board also use longer screws. Good idea here to use a 1/4" plywood underlay in case the whole floor fails. This is just about the poorest method of flooring, to be honest with you. I don't advocate it at all, and that's why I didn't mention it.
As always your Most humble servant, Joseph, the Wood Floor Doctor.