Some facts. Damon put a Progressive DYnamics 9180 on my RV, and a single pair of Interstate Work-a-holic U-2200's (about 220 amp hours) I had to water 'em every mothers day when new. more frequently as they aged.
I upgraded the battery by about 300 amp hours (Added batteries) and 4 years ago replaced the interstates (9 years old) with a pair of DEKA G-20's (230 amp hours)
Had to water 'em I think last Feb, for the first time. a month or two shy of 4 years.
XANTREX recommends no more than 30% C/20 that is for a 200 amp hour battery bank (rounding to make math easier) 60 amps or 66 for my original Interstates. Now add in a bit for the chassis battery (75 AH roughly. ) and loads. the 80 is OK.
BUT the SLOWER you discharge... THE SLOWER..(up to a point) the longer the overall life of the battery. I think Trojan suggests 10% of C/20 or 20 amps for that same 200 amp hour fictional battery bank.
Of course the trade off is generator run time. the slower. the longer
ASo for 2 pair I'd go with the 9180+Wizard (or 9280). in fact.. I DO
