Those are pretty good charge air cooler numbers, and 25 psi is a lot of boost. I love the thought of making things simpler, and I think using radiator fluid for an air to water would definitely make it less complex. My apprehension is that although a water to air intercooler is more inherently efficient, if you are using radiator coolant that is say 175F, in your analogy above, even if it was 100% efficient your post CAC would be at best 175F. In reality, reasonable efficiencies would yield a post CAC temp above 200F. That's twice as high as your air to air front mounted CAC measured 100F temp.
The reason air to water is popular in industrial applications is the use of a cooling tower, which allows a nearly limitless supply of really nice cold cooling water. In production automotive and truck applications with internal combustion engines and air to water CACs, a separate coolant system is used. Two really good examples are the supercharged E55 Mercedes engine and the 6.7 Powerstroke, both have separate cooling systems for the intercoolers circulated with an electric pump.
Again, I don't want to hold anybody back from fabrication, and I really hope there's something I am overlooking as the simplicity of the use of the existing coolant system is an interesting thought, I'm just not sure I can get past the fact that thermostats generally open at around 195F, which means at almost any point in the system, the coolant isn't really "cool" when it comes to charge air temps.
Just my .02, which usually isn't worth that much