You can change the direction of the vent on a dryer if it helps. You should be able to see the circles on the side of the machine you can punch out to do so. I'm not sure about venting down though, don't see how that connection could be made when putting the dryer in place.

You could also do a stacked setup if that gives you more vent options, the dryer is always on top.

I haven't read all of the comments on here but I think I know how you can get the platform suggestion to work, assuming I understand the issue.

I am assuming the main issue is that just putting in a vent in any configuration from the machine will result in it hitting the wall. Having the vent go through studs is a bad idea but there shouldn't be any issues running the vent parallel to the studs. So the vent can go into the wall, down to under the platform, come out of the wall, then go where it needs to go.

I'll see if there are any pics or diagrams give posted but if you haven't, those will be helpful.

On my dryer which is stuck close to the wall vents into a narrow rectangular prism that turns into a cylinder once it passes the width of the dryer and then vents via a flexible aluminum hose to the outside.

Could the pipe come below the dryer, then into the wall between 2 studs, then out of the wall into the dryer?

What kind of dryer? Many brands can be modified so the vent exits the side of the dryer.