Add a taps are a staple in my book.
I buy them by the 100's from lighttrader.com
In quantity, you can get them for as low as $.50 each.
18 Ga. cable is rated for between 600W and 850W per 100' depending on where you look.
I routinely run 15 36 watt LED fixtures off of one run, and the cable never even warms up.
here's a link to the ones we're all talking about steve.