Hmmm...different charging profiles.  Yep.  But the Optima will charge
effectively at 13.8 to 15.0 VDC.  The batteries don't talk to each other
when the alternator is running.  If your regular battery is OK with 13.8 to
14.4 charging voltage ,as most are, your deep cycle will work just fine.
The battery only sees a voltage source.

If you had 3 batteries in parallel and a 14.4 VDC source each battery would
"draw" only as much current as the internal resistance (which varies with
the state of charge) will allow.  A discharged battery is still around 10.2
VDC so if you had one discharged and one partially charged and one fully
charged and the alternator was supplying 13.8 VDC all three batteries would
be accepting charge albeit at different rates.  You wouldn't "burn up" or
"smoke" anything.

If the alternator is not supplying power, (motor off) then the batteries
would tend to an equalibrium state of charge in which each battery is at the
same voltage as the others.  A good reason to have an "alternator off"
isolation circuit.  Oddly enough the my vanagon came stock with just such a
circuit.

Smart, them chermans.

pensioner