Thanks so much for the spirited and sometimes helpful conversation.
I'd like to clarify a few things for those interested.
The trailer is not a full time residence. It is only a crash pad when needed. Something like the "man cave" that was mentioned in a previous comment.
I aim to be as environmentally conscious and neighborly as possible. I only use all natural/biodegradable cleaning products and my neighbors are aware of my setup.
The drain percolates approximately 15 gallons per hour.
The legality of the setup is important to me. I have no desire to break laws or codes. My understanding is that the trailer is completely legal as is, as long as it is not used as a primary residence and not stayed in for more than 30 consecutive days. I need to do more research on the drain. The recommendation came from a source that said it was ok as long as it was on private property. It seems to be working perfectly, but I understand that doesn't mean it's legal. (I will provide an update when I find a definitive answer on the legality)
Regarding the over arching question of whether to pee or not to pee - this is a much bigger question without a clear answer.
According to one poll of 1,000 women - 75% admit to peeing in the shower. Many do so more for environmental reasons than convenience as ~27% of household water is used to flush toilets. source - Peeing in the shower: Filthy or fine? - today > health - TODAY.com
The above aside, there are clearly plenty of people who object to the practice. I asked the question to the forum with regards to any potential concern to the trailer, not whether the practice was hygienic.
Of course you must aim for the drain, and remember - it's all pipes.