I've been trying to get the size of this picture to what will fit in HEE's uploader. Right now it's a one-layer jpg file, that refuses to shrink below 329 kB. I've tried a few online optimizers and they don't do anything. Ideas?

Try this website: http://compressjpeg.com/. It's the only one that worked for me after spending over an hour trying to compress from 200k to below 100k without ending up with a pixelated garbage square. Even Photoshop wouldn't condense it enough without losing most of the quality. It's nice because after you upload the picture you can click the settings button on the thumbnail and adjust the quality so you can get the highest rate with the lowest file size possible. Good luck!!