Welcome here.
I've done both.
I installed, or more correctly replaced the Battery Tender cable my dealer installed for me. It was routed to the right glove box. They drilled a small hole in the very back of the glove box just barely big enough for the SAE connector of the cable to fit through. I replaced the standard Battery Tender cable, which is only 18 ga wire and has a 7.5 amp fuse, with a slightly longer cable that is 16 ga wire and has a 15 amp fuse. It's not hard to do since the battery is just in front of the meter cluster and the glove box is just to one side of that and can be reached from up alongside the right fork (of course you must drill the hole going in through the glove box door with a long drill bit). The bigger wire is needed for 15 amps. My Slime mini compressor must have a 15 amp circuit to work. I have a few adapter extensions that plug into the SAE connector for plugging in a variety of gadgets. I have one that is SAE to standard 12 vdc socket. I have another adapter that is a Battery Tender brand USB connector (to have an extra one since the AK comes standard with one). I also have a 3 ft extension cord that is SAE to SAE and can be used with a SAE gender changer plug. I also carry a SAE to battery terminal clips adapter so I can connect to another battery for a slow charge (definitely not for jump starting since the wire size won't handle that).
I also have changed the oil and filter. The 600 mile oil/filter change did involve dropping just one side of that bottom panel. No need to remove it entirely. Have you seen the video of the gal who did a filter change without moving that panel at all? The 3000 mile oil change is just that... an oil change but not a filter change. This weekend I'll be doing the 6000 mile oil/filter change and I intend to do it this time without removing or dropping any part of that bottom panel. It can be done.
I bought the oil filter wrench that is specifically made for these oil filters to make it easier to do. It's actually a BMW filter wrench since BMW uses the same filters on some of their bikes/scooters.
Here is the link for that tool:
https://a.co/d/4tScRPqI wrote a few posts on doing the first oil/filter change in this forum (and another forum as well). Here is the link to my post and also the next 2 posts for more detail:
https://www.kymcoforum.com/index.php?topic=31882.msg223614#msg223614The 2nd post I showed the bottom panel dropped as much as I needed to. But with the new filter wrench I don't think I'll need to do that.
But if you really want to drop that panel I do describe how I did just that in the post I linked to here. I do recommend getting that filter wrench however. It will make taking off and putting on the filter way better. I've used one like that on other bikes but it didn't fit the HF164 filters that are OEM for the AK 550. BTW- I was just reading somewhere recently that HiFlowFiltro makes the K&N oil filters. I'm just sticking with the OEM since those are no different than the KN164 and are good filters besides. I bought a 4 pack of the HR164 filters from Amazon for less per filter than I could find anywhere else.
I'm not familiar with that Castrol oil but I am familiar with the needs for this bike, and other bikes I've owned, that has a wet clutch. That means the clutch uses the same oil reservoir as the engine. Is that Castrol oil JASO MA/MA2 certified? I usually don't give any recommendations about what oil to use other than that if your bike has a wet clutch, like the AK, use
ONLY oil that is JASO MA/MA2 certified or rated and says so on the bottle. I've read about too many riders who didn't and eventually, as in before the next oil change, ended up with clutch slipping and other clutch problems. Sometimes requiring some major clutch repairs. I used to use Rotella T6 5W-40 but that has become very hard to find. Now I use Super Tech 4-stroke full synthetic motorcycle oil (the bottle with the sport bike silhouette on it).
Be sure to check out the threads on the AK 550 in the Technical sub forum here. Lots of info on doing stuff on the AK hiding there.