Questions on redarc override switch and winching with it

Hi all, I am installing a redarc dual battery system and was wondering if I can wire up the start assist feature with a normal switch (as opposed to the momentary switch) so I can have the choice of using it for winching with both batteries or just one?
Also when using the override switch, does the starter motor draw the power from both batteries or does the second battery just slowly top up the starter battery?If so can this still have any benefit for winching if the start assist was kept on?
I realize that there are other ways to wire it up (marine switches,2 battery winching) but would like to know if the above questions can be done.
Cheers
Glenn