The compression ratio on the 4.0 is perfectly fine for FI and the proper selection of turbo will yield a seamless increase in boost/power.
Forced Induction generates torque which results in increased power whether at full boost or partial boost.
You must realize, for a turbo, boost, for the most part, is linked to engine load and not rpm, unlike a belt driven supercharger. This means that off road while crawling you may not produce much if any boost due to relatively low engine load.
If you've ever driven a properly designed turbocharger vehicle you could observe that while encountering a hill, with no additional throttle input, boost will increase as load increases.
Few people are wanting of more power from the 4.0 while crawling. Where it lacks is breathing in the higher rpm range. Modern turbos can be configured to cover a wide range of rpm relative engine displacement and power goals.
I've thought about turbocharging my Jeep and may in the future. The turbo would be mounted high with ceramic coated turbine housing. It Would be intercooled using a water/air system with an electric fan on the heat exchanger. For boost levels in the 5-6 psi range a quality FMU like the BEGI would suffice. You could expect a theoretical increase in power of approximately 33% at that boost level. I would rely only on the WG to manage boost.
For the Jeep application there is no need for additional boost controllers... you already have two, the WG and the throttle.
Dyno graph of one of our 3.5l BMW builds. This with no 'boost' controllers on a 200K mile, 1986, 'junkyard' engine. Notice the nice broad torque curve.