@Brian Roebuck what you haven't told us is how much lead you normally dive with in the skin. That's important.
The 100 will have 8lbs of gas in it. Assuming that you are using an AL plate instead of steel, that's an extra roughly 3-4lbs of negative buoyancy. All lifeguards, and we require all of our bsaic divers as well, are required to retrieve a 10lb diving brick from the bottom of a pool, and bring it to the side of the pool, in a bathing suit with no fins. You have an extra 2lbs, but also have fins on. If you can't kick that up, you really shouldn't be diving because you likely can't pass a diving physical. More importantly, the 8lbs is something you have to kick up regardless of any ditched weight since ditchable weight should never exceed the buoyancy shift of the wetsuit during compression. With a 3mm, that's 6lbs, so if you ditched, you'd still be kicking 8lbs of tank up.
Ditchable weight is a ridiculous notion in any diving scenario and is not something you should worry yourself with. Dive a balanced rig, and if you're a couple pounds heavy, so be it, it's not the end of the world as you can see with the example above. It's when you are diving some stupid rig like a 7mm farmer john at 100+ft where the suit can lose something like 30lbs of buoyancy due to the depth compression, AND are starting the dive overweighted by 6-8lbs like most divers that you have to get concerned. At that point, to quote
@cerich, that's an equipment solution to a skills problem and you need to address the real problem before you try to bandaid it with ditchable weight. Planning to ditch weight only adds risk to your dive as you are increasing your chance for a runaway ascent and a subsequent embolism