I'd recommend a 600lb spring if you're going to run a bumper and winch. I'd go 700lb if you're going to run dual batteries, winch, bumper, skids, sliders, etc. I never judge the weight solely on what's hanging off the front of the vehicle - I look at the overall weight and plan accordingly. All that weight in the middle (sliders, skids, etc.) is distributed to the rear and front and I basically account for what type of spring to run based on the overall weight. I usually build heavier "overland" style vehicles with all the goodies - so, they end up being heavy. I'll see what my truck weighs - maybe get it on a scale this weekend and report back.
I can tell you my Land Cruiser was 6,700lbs. But, it was probably one of the heaviest builds out there - African Outback drawers (fully loaded), Milford Half Barrier, Power Tank, ARB Fridge, Dual Swing-out Rear Bumper, Rear Ladder, 35's, INTI Roof Rack, Aux Fuel Tank, Sliders, IPOR Skids, Warn M12000, ARB Bumper, Snorkel, Super Charger, Dual Batteries, Water Tank, etc.
My bet would be that my Tacoma is pushing 5,000lbs. But, it may be a little lighter than that.