Finally, the time came to power up those high current led´s.
The LED´s does work as expected, even without a current limiting resistor. Using PWM controlled half-bridges the intensity can be adjusted.
At the very lowest setting, it is possible to look at the LED´s, but just turning up the PWM a bit makes the lamp to bright to look at.
At high intensity there is significant heat development, so my original approach seems to hold true.