you can tee above the first trap and save money on getting a second trap. That seems the easiest as, drain lines aren't that complicated.
I would split after the first valves so that you can shut it off better if there are any leaks, and you don't have a leak before the working valves. Whether you install a second set of valves or really even a third is up to you, and will only provide greater flexibility in the future for control and repairs. In my opinion, keep it simple.
I think it's too bad that everybody's decided to turn on drugs, I don't think drugs are the problem. Crime is the problem. Cops are the problem. Money's the problem. But drugs are just drugs.