Out of curiosity, I just looked at the dining plans, and even the basic (1CS, 1TS, 1 snack) was like $1500!! I NEVER spend that much on food when I'm alone!! Typically I'm looking at MAYBE $100/day for food on a solo trip, and that's if I'm extravagant on snacks/beverages (more likely to happen in EPCOT because World Showcase), so for a 5-njght trip that's like $500 tops for food. I can definitely save that extra $1000 for something else!!
I would take a good look at the menus of the places you're thinking of eating, think about your eating pattern when traveling and/or in theme parks, and do a rough price-out to see what you come up with before committing to a dining plan (I know I could still add it if I wanted to - that's how I know what the price for mine came out to).
Like several others on here have posted, I might do 1 TS meal a day (in my case it's often a character breakfast around 8:30 or 9 since I'm not OMG MUST BE AT ROPE DROP - I can eat my fill at the buffet), and then the rest of the day is little snacks here and there. I will get the refillable mug, and I'll carry a refillable water bottle into the park with me (as long as they keep allowing that) - and more often than not, I'll bring Luna bars to eat for breakfast on non-character buffet mornings (occasionally I'll do a "linner" at one of the World Showcase restaurants) and to throw one in my bag to have later in the day.