Ducted air/fan idea?
I like a high efficiency air cooling system better that the all water for many reasons.
More parts you have.. more parts to break.
Theres no way your telling me that the water cooling system is good for anything other than an Onroad car.
What happens when you flip? The marine example might work well though.
Have a little tunnel blowing air on a mini radiator and circulate the water with a small pump powered by an additional 6V hump pack or something.
But I'm definitely putting that funnel on my buggy
ram