https://minnkota.johnsonoutdoors.com...-battery-guide
Your basic wiring should be as shown above. You didn't say if you have a circuit breaker wired in. If you don't have one get one. You've spent a lot of money and the circuit breaker is cheap insurance. The store that sold you your trolling motor should have them. The above link give some info.
Your trickle charger isn't going to cut it. It could take a day to charge just one battery.
I would not get a 24 volt charger for your batteries. Most likely the only thing you will be able to charge will be your trolling motor batteries.
I would get a 12 volt charger that has at least 10 amp output. You could use this to charge your trolling motor batteries and the batteries in your car or truck if need be. The 12 volt battery charger would just be more versatile. Just a quick note that most battery chargers have the capability of charging lead acid, AGM, lithium and possibly other types of batteries. You need to make sure that you select the correct mode. Also, check to make sure that it supports LiFePO4 batteries just in case you make the switch.
If you leave the batteries installed in your boat you should unplug your trolling motor while charging. If your trolling motor is wired directly to your batteries you should disconnect the trolling motor leads. The jumper does not have to be disconnected.
You can connect your 12 volt charger to one of your batteries and charge until it is fully charged. A smart charger will have an LED to tell you when it is done.
Then connect your 12 volt charger to the other battery and charge it until it is fully charged.
Someone mentioned a two bank charger. These work really well. The charger will have two sets of leads, one for each of your batteries. Connect one set of leads to each of your 12 volt batteries and then plug in the charger. These are very convenient as both batteries are getting charged at the same time.
I'm using a NOCO GenPro 10x2. It's a two bank charger that puts out 10 amps per bank. It handles lead acid and LiFePO4. It's new for me for this year and so far so good.
There are other good chargers out there. Chargers that only charge one type of battery will be less expensive. Lower amp chargers are also less expensive. In your situation, my minimum would be a single bank 12 volt, 10 amp smart charger that matches the type of batteries you own. eg 12 volt lead acid