electrical problem

Hopefully someone could give me an idea what to look for out stear me in the right direction.

I'm living in a 97 Sunseeker, when we first started living here, we tried to compensate with electrical heaters to instead of using our gas. Bad mistake on our part because we were tripping breakers left and right, decided to pull the breakers out and replace them. Thus discovering a lot of the wires were singed, burnt, and the neutral safety bar almost completely melted. We learned our lesson on our 30 amp system. Not to pull too much. A lot more conscience of keeping certain things off when we use something that pulls a lot of amps. Well on safe keeping, we replaced all the circuit breakers, cut back on the wires to clean them up, rewired, replace neutral safety bar and all that. After replacing the one breaker, it's a breaker with gfi protection, we started having problems. This breaker controls four outlets, the one next to the bathroom sink, kitchen sink, under the dining table, and one in the storage compartment outside. Anytime you plug anything into any of these outlets,  the breaker trips. (even just charging a cell phone) I was told that the wires could be grounding out somewhere in the line but when I take the pigtail from the particular breaker off of the neutral safety bar, it no longer trips and I can use them fine, but then I no longer will have the gfi protection for these outlets.  I thought about just keep the breaker disconnected from the bar and not have it gfi protection but I would have power. I'm just afraid that when I leave, the place will be up in flames. I replaced the breaker just in case the new one I got was faulty but to no avail, same problem persist.

Am I missing something here?

Can you get a non GFI breaker to fit into that slot and just use GFI outlets instead. If you are lucky one GFI outlet will protect all 4 outlets

what kind of shore power are you hooked up to? extention cord,30 amp or 50amp ? have you checked the voltage at your rig? it sound like you have a low voltage situation.

In RV or Marine applications, the AC power source in not bonded to the safety ground. You said you replaced the "neutral safety bar". Do you mean the bar that all of your white neutral wires attach to?  You may already know this, but I'll explain anyway.
Your power panel should have two connection strips (buss bars) that are used for the 120V AC circuits.  One connection buss is for the safety ground (bare copper wires from each circuit) and one connection buss is for the white insulated wires of each circuit.  A typical 120VAC circuit will have three wires - black (hot), white (neutral) and an un-insulated bare copper wire (safety ground).
The black wire for the circuit goes to the circuit breaker, the white wire goes to the neutral buss and the copper wire goes to the safety ground buss.  The neutral bar must NOT be bonded (electrically connected) to the ground safety bar.  This is typically done by insulating the neutral bonding bar's mounting attachment from the panel frame using a non-conducting standoff for the buss bar.  So, make sure your replacement neutral safety bar is not electrically connected to the power panel frame.  I think once you isolate the safety ground and the neutral, your GFI breaker will work fine.

I suspect the GFCI breaker is not installed correctly.  However, regval is correct that the neutral and ground buses in an RV must NOT be bonded together, nor can ground wires be connected to the neutral bus or vice versa.  If you replaced either the neutral or the safety ground bus, take another look at your work and make sure they are isolated from each other.  The ground bus should have a connection to the vehicle frame, though. The vehicle is supposed to be grounded to the shore power ground when connected to external power.

Unlike regular breakers, both the hot and neutral are connected to a GFCI breaker. The black "hot" wire to the outlets goes to the LOAD or HOT terminal and the white wire to the outlets goes to the NEUTRAL terminal.  Most GFCI breakers have a short white wire pre-connected and this goes to the Neutral bus in the load center. Do NOT connect the branch circuit neutral to the white wire on the breaker.

The GFCI breaker will trip whenever the amps measured on the Hot/Load terminal and the Neutral terminal are not absolutely identical.

Is one of the four outlets already a GFCI?