Hi Jacob,
If you really want to build your own, custom, pre-pack, I suggest you add the elements one at a time, to test for tolerance. It is a rather slow process, but it helps in knowing what supplements are causing you side effects, and which one are well tolerated and help the alleviate POIS symptoms.
If you know that supplement A is well tolerated, then next time you try A+B. If good, next time, you try A+B+C, and so on.
To give you an idea, it took me about 6 months to get to a pre-pack formula that reaches 90% relief. But early in my testing phase, after a few weeks, I already had some 50% on average, which is already significant.