The difference it makes is that you can have continuity through a 3A fuse, but the converter will blow it if you try to run the trailer through it. You need to find terminals that are directly connected to the battery plus and minus, or at least through a large fuse. That said the new converter should connect at the same point that the original charger connected to the fuse panel. Also, it would be hard to go wrong connecting the new converter directly to the battery, or on the other side of the disconnect switch from the battery.
"You cannot reason someone out of a position they have not been reasoned into"
Al, K5TAN and Missy, N4RGO
2002 Classic 30 Slideout
2001 Safari 25 RB Twin (Gone, but not forgotten)
2013 Dodge 2500 Laramie 4x4 Megacab Cummins
WBCCI 1322, TAC FL-39, AIR 82265