I think what the slug is trying to say is he is planning to set up his bump stops just like described above, then after he does that he want to know how high he should build his suspension above that.
This all depends on intended use. Jeep wranglers only have about an inch of uptravel stock same with many 4x4 1 tons in the front. If you don't want to hit rough stuff fast you don't need much uptravel at all. Yeah 4 inches sounds pretty reasonable, there are lots of rock crawlers running around with no more than that.