Since the cables got cut off hopefully the ends that are still accessible are long enough to hook back up.
This might be a good time to install a BATTERY DISCONNECT SWITCH on your trailer cross frame. You can install your POSITIVE wires to the switch terminals and then run a new short cable from the switch to the battery terminal. If the white ground cable is too short now you can also purchase a longer length with ring terminals already on them. You should be able to find both ends real easy as it will be close to the battery install.
You will need to have all of your wiring setup with ring terminals on the ends and you can most likely replace the WHITE FRAME GROUND cable and the smaller POSITIVE CABLE from the breakaway switch. The other LARGER POSITIVE CABLE comes directly from your CONVERTER/CHARGER 12VDC POWER DISTRIBUTION panel area and may not be easily replaceable. This means you may have hand crimp a new ring terminal on the end of this cable. Making up the cables on your own might be a pretty good challenge without the proper crimping tool. Smashing them on with a hammer does not sound like a good idea to me but I hear others do that..
Your TENT TRAILER not having a underbelly covering will make it pretty easy to trace down the cable and replace them if they need to be longer. I picked up one of those $60 8-ton hydraulic hand crimpers that does a nice job of crimping on ring terminals. I'm always working with battery cables it seems.
My batteries are mounted across the tongue frame and I have three BLUE SEA BATTERY SELECTOR switches installed across the frame cross member which is close to the batteries. With these switches i can select any of the multiple batteries to use or disconnect from the system. This also gives me ring terminal studs to connect too so all of my battery cables are installed with ring terminals on each end. make for easy replacement or upgrade to larger cables etc...