Your trailer
probably has a WFCO 8945 or 8955 power center. Both contain a converter/charger that serves to provide up to the rated power (45 or 55 amps) with the remaining power available for 3 stage battery charging. You can download the specifications, owner's manual and troubleshooting/technical information here:
https://wfcoelectronics.com/product-...f-8900-series/
Your question about multiple chargers has already been answered: No you can't use multiple chargers. The reason is because almost all "automatic chargers" (ones that have multiple charging phases) are voltage driven. As the battery voltage increases, the charge rate (from the charger) is decreased to prevent overcharging the battery. So, if you have two chargers connected to the battery, the "line voltage" will be the output of (pick one) charger which would be "monitored/sensed" by the other charger and act as the means to reduce charge power from that charger.
So, if you have a 55 amp WFCO converter/charger in your trailer and you connect a "cheap 1 amp HF trickle charger" to the battery, the 13.4 volts from that HF charger will "tell" the more powerful WFCO that the batteries are fully charged and force it into the "float mode" (trickle charge mode) which would prevent your battery from adequately charging.
In other words, one battery charger will "fight" any others that you might connect, making it impossible to charge your batteries from multiple chargers. That's why any "professionally installed solar/battery/multiple charging system has automatic or manual switches to remove all but one charger from the battery feed.