16-35 L 2.8 II, 70-200 L, 50mm 1.4 cover almost all current and future use (I have 50mm 1.2 instead 1.4). plus one 580 II flash with cybersync trigger transmitter and receiver.
buy zeikos UV filter glass, just cover dusts (10 dollar on ebay, free shipping).
add one tripod with ball head (both should have 17 lbs load capacity}.
you are set near 4-5 years.