I'm putting a sink on the L of my kitchen. I drew up a rough sketch of what I think the rough plumbing should be. I cannot run my drain and vent under the cabinets of the kitchen as in a traditional island vent setup b/c my attachment point to the drain line is 6" above the finished floor. The drain pipes will be 2". I have a few questions: 1. Does this setup work? 2. Can I downsize the vent pipes to 1 1/2"