Your 45amp converter will only be doing about 30amps at first and that will quickly taper down in amps, so it takes forever (all day) to recharge the battery.
Forget that 40amps for an hour with the 7345 on a generator. You could get that if you have a 40amp charger, at 14.x volts (14.6 is good), and the battery is low enough to accept the 40 amps that long before tapering starts (the battery acceptance gets less as it rises in state of charge)
You don't say how many AH you need to put back in the battery bank in that hour and how low the battery is when you start. It is easy to get a rough idea how long it would take to do how much of a recharge if you have some info on what you are starting with.
(You can get 45amps from the 7345 but only in special circumstances not related to actual camping. EG on short fat wire to the battery where the battery is also supplying an inverter powering something that makes the inverter draw 45amps from the battery. Now the 7345 will ramp right up and feed the battery what the inverter is taking---but only if your 120v supply to the 7345 remains near 120volts and does not drop down to 105volts or whatever!)
