a good charger will taper the charge to lower amps as it gets closer to full charge which should prevent overcharge damage. If you need to refresh your battery at midday suppose I would go with the bigger one. Another thought is that perhaps if that is the case go to a multibank system so you have plenty of amps for a day on the water and then charge at night. The bigger charger is going to be heavier and larger think space available. Would it matter if your charge is complete at 3am versus 5am? Make sure your charger has ventilation to to get rid of heat and always go with the largest wire possible and a properly rated 60 amp typically marine rated circuit breaker that you can reach. Had a few problems with powerpro chargers, they replaced them readily but a hassle to reinstall and the holes seemed to always be different. The last replacement has been in service for 2 years now and seems to be holding up well, is has a conditioning mode which should keep the batteries from sulfating and it seems to be doing it's job. Have had to increase the battery ventilation a bit, was getting condensation in the area even from sealed batteries, probably a bit of heat is generated during charge.