Thanks for the feedback. I'll take your advice here.110a x 28v = 3,080 watts.
Theoretically, that's within the capabilities of your generator. But...there is also power factor to consider.
If the charger has a power factor of 1, then it will draw 3,080w from the gen to supply 3,080w to the battery. But if it has a power factor of 0.8, it will draw 20% more from the gen to supply the same 3,080w to the battery...which would exceed the 3,500w continuous load rating of the gen.
Of course, the Samlex can be programmed not to exceed the limit of the gen. But that is going to reduce the amps to the battery. If that reduction is around 20%, then you are only going to shave 1 hour off your charge time.
Personally, I would choose to save the 15% cost since you don't need a 4,000w inverter. Charging at 70a and still having 1,500w available overhead to run computer and/or a/c would be my choice.