Smart move to upgrade to LED lighting and 4 T-105's in series / parallel will certainly carry you overnight or more like 2 nights easily. One more upgrade to consider to get the most of a battery setup like that, would be to upgrade your converter and wiring to match. This would give better charging capabilities for a shorter generator run time.
Depending on converter size a 2000 watt would be fine. No doubts a 3000 watt generator would power all your needs plus ability to use more 120 V loads.
As for generators, well I'm a fan of the Champion brand. (Best bang for the $)