You can stop every hour to run the charge on the towd an not make any difference in reality. You will pull more charge starting than you will replace by a 15min run, add in the time you have been on acc. Make sure all items radio, heater/ac etc are in the off position. If you have DRL's they will drain the battery also. My hyundai has the lights come on whenever the key is in the ignition and we ran the battery down on 1st tow. Added a charge wire and no issues since. An alternator is not real efficient in battery charging short term. RPMS need to be around 1500 rpms to activate the charge circuit, although it will charge IF you get it over 1500 and then idle.
Easiest is to add charge wire to battery. Some put in diodes I have a fuse in line. pretty simple to do. I think we ran 10 ga wire for the charge line.