Can I drain a toilet straight down if it's vented close to the floor the toilet is sitting on? Unfortunately, the only access to our sewer line is 24" straight down but there's space enough to vent anywhere along the vertical. Thank you in advance.

See the enclosed drawing and if it will work for you. The 2" vent pipe should be installed under 45 degree angle. You should have enough space to make the turn. Hope it helps. Back to you. Milo