Sean, I just gave your "Sneaky Pepe" a download and listen. Cool stuff and nice work. But I do understand what you mean about the bass. The mix is clean, very clean and the bass is there and not covered, but it does sound like it's in a hole. There's a couple of things happening, I think...
First of all it sounds like it's in a "hole" much because the lead guitars on the sides are extremely up front in the mix. Having those two so "close" to the listener and hard panned at the same time instantly creates a 3D "frame" around the mix that automatically is going to make anything in the middle of the picture sound more distant. I'd look at decreasing the dynamic range between the guitar tracks and the bass track; not thorugh compression, but just by pulling back on the guitar levels a taste (just 2 or 3dB maybe, though that's a guess), and simultaneously bringing the bass level up just a bit by about the same small amount.
After doing that, I might also consider softening the pan on the lead guitars, bringing them inside just a couple of degrees, so they are not quite so obvious a frame but still give you that mice stereo effect. Then I'd fill the side with a little wet reverb return on those same guitars to fill in the edges but with a softer edge than there is now. This should help integrate the guitars with the rest of the mix, putting them on a bit more equal front-to-back footing without losing the guitar's prominance in the mix.
And third, the guitars sound really good...and that's actually part of the problem in a way

. The guitars have a nice warm rounded bottom end to them. That is actually making your bass with it's surrently comprimised signal path sound a bit thin in comparison. I wouldn't touch the guitars EQ-wise if I didn't have to, but you might do well to accentuate the slap of the bass a liitle at somewhere around 3-4kHz to give it a little more definition. That is, if there's anything there work with. It could be that your jerry-rigged signal path for the bass is just sucking too much life out of it too, and if you try boosting that stuff you'll just get mud. You can only try it to see if it helps or not. But get yourself a SansAmp bass DI or something along those lines and you'll be much happier, I'm sure
A small non-related note: There sure is no lack of bass on your web page!

Your bass cleff backgorund graphic is so prominant that one cant read most of the text

. Just a friendly surregtion that maybe you might want to lighten up that background image to a ligher shade or gray or something so that it does not camoflague the text. Just an idea...
G.