Have you guys seen this at
www.idot.com:
Morex Car Power Regulator Kit
Input voltage: 11v - 15.5v, unregulated
Output: 60W
4A at 3.3v, 4.5A at 5v, 1.5A at 12v
It includes a regulator and a 60W DC-DC converter. May not survive crank, but it has a wider operating range than the ITPS.