New Owner. Question about TM battery.

After years of research we finally purchased a 2002 3124KS (taking delivery at the end of April). I would like to thank everyone for all the tips and good advice. This forum is great for TM owners. I have a question about charging the TM battery through the tow vehicle. I was told connecting a heavy gauge wire from the + side of the vehicle battery, through a fuse and directly to the 7 pin connector is not recommended (will cause damage to the vehicle battery and/or charging system). I know the if the vehicle is turned off and the TM is connected, the vehicle battery could be drained but that does not concern me. The TM will be connected only traveling to and from our camping destination.
Can the vehicle charging system or battery be damaged connecting to the TM in this way? Is there a better way? Any advice would be appreciated. Thank You.

You're doing this just fine.  While robust wiring, properly fused is desirable for it also can result in heavy inrush currents during recharging which bad only for the fuse.

More times than not the wiring is relatively light, or the connections have voltage drop and these work to limit these initial charging currents.  I'm guessing that your tow vehicle will have no greater than 12awg back to the connector anyhow.  I think 30amp fuse should be an OK compromise.  If you flatten the trailer battery and then blow a fuse upon plugging in, it's understandable.

If your Explorer is equipped with the "factory tow package" (did it come with the 2" hitch receiver, and 7-pin plug installed?) your trailer battery is being charged whenever you are connected to the tow vehicle and the engine is running. Ford includes a relay in the tow package that sends voltage to the battery only when the key is on and the engine is running. The trailer battery cannot discharge the vehicle battery when the engine is shut off. I've had 3 Fords with tow packages (92 thru 00) and each one worked that way.

Verify this information with your dealer.

If you don't have the "factory tow package" install an "isolator" between the vehicle battery and the trailer battery. That is a diode that only allows voltage to travel from the vehicle to the trailer. Cost is about $50 and you can install it yourself in about 1 hour. ;D