First off, if I were building a forced induction off-road vehicle for low speeds, I'd go with a supercharger, and probably a centrifugal or a twin-screw design. Easier to keep cool with less "ram air." Having said that...
There are a number of ways to keep air charge temperatures down with a turbocharged engine. Of course, the simplest (short of very low boost pressure) is the use of the air-air intercooler, but you run headfirst into the fact that the heat capacity of the cooling medium is the same as that of the cooled medium, with the sole difference being the volume of cooling media available. That's a big difference, but at low vehicle speeds, not low enough.
The next way would be with an air-water intercooler, but there is another decision to make here - what to use for water? Do you use the water from the cooling system (which can work well, assuming very high boost pressures/therefore high temperatures or a very efficient cooling system)? Do you plumb an entirely separate cooling water system? If you do, where to you put the second radiator to cool the cooling water, or do you do an "icebox" for short runs? Either way, you have to figure out how much water the system can hold (or if it holds enough for both jobs) and make sure you can keep it circulating fast enough to do the job(s). I've seen A-W intercooler systems using engine coolant, but it's a pain to set up.
So, if you use the air-water job and want to use a separate water circuit, you generate a whole slew of plumbing problems. First, you have to make absolutely sure your intercooler core DON'T and WON'T leak - hydrolocked engines aren't fun. Then, you have to route the hoses to and from the intercooler - with attention to keeping the cool hose cool. Run them into a pump somewhere (keeping it cool as well - you are trying to remove heat, not add it,) and still stick a useful reservior and a second radiator somewhere - and that second radiator needs to be exposed to ram air as well, or your water gets heat soaked and you don't get any benefit from it.
Now, do you use just water, or do you do an "ice-water" cooling system? Do you use "wet" ice? How about a two-champer reservior and "dry" ice? Either way, you will lose the excellent cooling right away and you'll likely notice the decrease in power.
Now, a couple interesting ideas I have seen are these...
1) Use liquified gasses to cool the intercooler on an air-air setup. I have seen a couple setups that were rigged with CO2 syphon tanks to blow liquid CO2 over an air-air intercooler on demand, and I've heard of it done with liquid nitrogen as well. Again, the capacity of the extra cooling is limited to the amount of cryo gas you can carry around and how often/cheaply you can gt it filled, but it's a thought.
2) Refrigeration. It is possible to modify the air conditioning setup to use the evaporator as an intercooler core, and have true "active" charge cooling. This is a measure for relatively high boost pressures, as you would have to offset the power drain of constantly running the air conditioner.
Of the two, I'd probably use the former (with some sort of "fog" nozzles) for anything under 40mph cruising or for low-speed pulling. That, and some rather large hood vents...
5-90
