Did you install it under the hood? I think using o-rings on the battery with the SAE connector is the best.
I think you might find giving the battery a full overnight charge maybe once a month will greatly improve things, unless your higher amperage drain continues.
In the winter you might charge more frequently if you do more short trips with the lights, wipers, and heater on.
Yes, I direct-mounted it under the hood using the o-rings it came with. Earlier in the thread someone else had suggested not getting a 'dedicated' direct-mount one like this, and instead getting one with alligator clamps that could easily be moved from vehicle to vehicle. I can certainly appreciate why that option might be attractive to some, but for me it made total sense to get the direct-mount one and install it under the hood. I got it all rigged up so that just the male end sticks out of the front of my vehicle. So i can go and plug it in without even needing to lift the hood at all, which is super convenient. I saw that NOCO even makes flush-mount ports you can install on an exterior surface of your vehicle with a weatherproof cover/cap. With those you just open the cover and plug your extension cord into it. I really like that, too, but it looks like you have to use a 2 inch hole saw to cut a 2 inch hole in your vehicle to install it. I'm not overly comfortable doing that myself at this point.
So far I've been using the charger on days when I'm not driving my vehicle and have had no issues, of course. I also bought myself a DC clamp meter and have been monitoring the draw a bit (when not plugged into the charger, of course). With the doors locked, the draw seems to fluctuate between about .08 amps and .20 amps, depending on how I position the meter. It seems to be quite sensitive, and I'm honestly not sure how accurate it is. I paid less than $40 for it from Amazon, just so I had something to try to continue monitoring this with. Looks like you can spend hundreds (literally) of dollars on them, but I wasn't about to do that.