So the General thinks he's going to be able to succeed where the divine Julius fell short? Certainly bold, that's for sure, but there is historical evidence that it was on Augustus' radar. In order to satisify the curiosity of the general, it would make a lot of sense to review Julius Caesar's attempted invasion of Britain in 55 and 54 BCE.

On the Regnenses: we here in Mission Control think this is a place where the Demiurge has widened the W62 tolerance--because we don't know much about the make-up of the tribal structure in 29 BCE, but we do know something of the Regnenses ca. 100 years later, the TSTT seems to be filling in a gap with the educated guess that you might have found the Regnenses in the same region in 29 BCE. You may therefore proceed on the assumption that what was true later was true in the time in which the Recentii now find themselves. You may also wish to consider how Commius of the Atrebates worked out for Caesar.

To fuel discussion:

Caesar and Britain
S. G. Brady
The Classical Journal, Vol. 47, No. 8 (May, 1952), pp. 305-316+348
Published by: The Classical Association of the Middle West and South
Article Stable URL: http://www.jstor.org/stable/3293057