Once you have the wiring such that the converter is maxed out, there is no point adding more wire unless you plan to swap to a higher amp converter in place. As you noted, you are getting the max amps now.
A few years ago, I decided to improve my 7355 converter (mid trailer) connection to the battery bank up front, since I could only get 25 amps or whatever at its 13.8v.
I ran a 20 ft length of copper water pipe under the trailer and wired it at each end to battery and converter to run in parallel with the frame on the neg side. Boom! Big increase in amps to battery.
Then I added a run of fat wire on the pos side in parallel with the existing pos wire. Boom some more! Using the 7355 as a power supply, not as a battery charger, I was now able to get 56 amps to the battery. Just for battery charging I was able to get more like 40 amps on that same pos and neg path instead of 25 amps. of course with that 13.8 single voltage converter, I was not able to test for amps to a battery at 14.4v.
So I am a believer in parallel DC wiring, but you can get it wrong. Eg, if one of the wires fails, the other should still have the ampacity to run the amps without melting. The one wire will have a huge voltage drop, but that is not melting. Different issue.
The idea is to have both paths in parallel take about half the amps, but they will actually do it in proportion, so you can have it where one is doing nearly all of it. In that case it might not be "worth it" to have the other one.
