I have built many an oversized costume. This year, I was 18 inches taller wearing a long black cloak and robe with no face showing, carrying a roughly 12-foot-tall scythe and wearing a large hourglass on a chain around my neck.
Last year, I was slightly stilted, roughly a foot (I am 5'10 naturally) and also built up from the shoulders and head slightly as an undead Celtic barbarian with a massive 6' x 10" sword that I swung at "challengers" (ToTs)
Another time I was a 12-foot-tall Scarecrow, leaping out at people on stilts from a scene I setup to make sure I looked less-likely to have been an actual person and just another lawn ornament.
Another time I was a little taller still, with a 12-foot armspan and had rigged a setup where I would operate my costume from the middle of it (to keep the knees in the right place) by stilting myself 18-inches taller and then adding a rig built up from my shoulders to the head I had made, so that it would tilt and pan and rotate the same way I moved my head four feet below, via linkages and a helmet. The arms, I controlled by being able to reach only to just after the elbow, where as if I were to extend my arm, the rig would do the same, but allowed within my design a means to control the wrist up and down and also make the wrists able to twist/turn, in a realistic sense. It was fun running around in this 150+ pound costume all night, but my costumes tend to be a tad heavy.
Let's see if I can dig up some photos.
Here is my Barbarian costume (And a Minion) and behind us, you see the rig I built to showcase my costume from the year before (Which was the big one I described in the previous bit) as I do this every year, to fool children and leave echoes of my previous costumes.
For a sense of scale, the skulls you see on my shoulder are life-sized. And heavy. Very heavy.
Here is my Scarecrow, but to be honest, this is ALSO from 2011, and is the rig I built to re-create my costume from 2008, which is the Scarecrow I told you about.
Here is my big Daemon Skeleton costume with the complex-sounding linkages and whatnot.
The funny thing is, with all the complex things I build, the countless hours I spend making them (all by hand) and money I invest (Four-Digits at times) into arranging Halloween costumes...I only wear them once. Except the Scarecrow. I wore that again, this year on the thirtieth, whilst helping my Sister cater a Halloween event at her job as part of her last-day celebration. I also took it out to the side of the Highway (right outside is the tourist section of Us192, thirty seconds from Walt Disney World) and danced around, just because I could.)