That test shows the converter does do its stages, but does not show what happens when you try to recharge low batteries using the 14.4v stage.
One test would be to start with low batteries (12.2v say) and not use the Wizard, but just see if the converter will go into the 14.4v stage by itself. If it won't, and you need to use the Wizard to make it do 14.4v, then you know you need fatter wire---if you want more amps at 14.4
So the next thing is to measure how many amps you are getting on low batteries with the existing wire after you force it into 14.4, and then decide if that is enough amps.
The big selling point of the PD IMO is that, unlike other some other converters, it does have the CW so you can force it to do 14.4 when it (and the some others) would not do so on its own. This can make up for having thin wires to some extent. Is that extent enough in your case for your needs?
If you don't have access to an ammeter that will measure 45 DC amps or so, then you would have to do some timing tests to replicate camping recharging but this can be a pain.
Another problem with backyard testing of converters is the 120v input you use. You can have lower voltage on an extension cord from the house than the higher voltage you get from your generator. Low 120v input voltage hurts the converter's DC output. You might need to run the gen for hours in the backyard to get the true picture.