You can use a 40a VEC1093DBD instead of buying a second converter that only does 14.x to use in that role. The 1093 will do 14.8 and also 15.7 for equalizing (which is also how to get the SG back to baseline)
No installation required! :)
Next problem is your portable generator limit on how many converters it can run at the same time. The PD already is using a lot of VA.
The VEC1093DBD uses about 785 when doing its 40a. You can perhaps run it and the PD 55 together and get about 90a which is fairly good recharge time on four batts. If the gen won't do both with the VEC at 40a, run it at the 20a setting. That is still about 70a total charging.
I use various chargers all at the same time to get more amps and it works. With the VEC, get it going first , then turn on the converter. Sometimes it doesn't work the other way around.