First thing I would do is get a clamp on amp meter and throw it on your positive battery cable. That will tell you the amps you are using. You don't say your battery size but my best guess is that if your batteries are like new...you probably have 150-180 amp hours which translates into 80or90 USABLE amp hours. Divide the usage you see on the clamp meter into the battery capacity to see how long you have to dead flat under normal circumstances.
I am also going to suggest that if you have had flat batteries repeatedly...testing good...is not the same as retaining full capacity so you are likely far short of "like new" even though the batts are good enough to use.
If you see a good sized draw on the batteries with the clamp meter...next step is pulling fuses as suggested. Watch the amp load drop as you cut stuff off and you'll know where your draws are coming from AND how big each is.
Make sure your clamp meter does AC/DC current (amps) measurement. This one from Amazon will do the job reasonably:
A 10 amp draw will take your batteries to dead flat in 15 hours or so if like new. You should not let it go more than 7-8 hours without a recharge.
Double the number for a 5 amp draw. etc. etc.
If you're not seeing a heavy draw...then your batteries aren't really in good shape even though serviceable for short periods.
Good luck and let us know what you figure out.