So I've been thinking on installing an SAE power socket using 10 awg wiring behind the seat of my 800ex and connecting straight to battery for trickle charging, etc.  I could just quick connect and never remove battery cover.  Has anyone done something similar, and has it worked good to charge or jump without frying the machine?

I used a bit heavier wire (cannot remember the gauge but about 5mm wire dia) and an Anderson plug which are easily available here in Australia. I have the second plug with about 2me (6FT) of wire so I can jump start someone else, or they can start me if need be. When charging of my battery is required I connect the charger clips to the Anderson plug.
https://www.ebay.com.au/itm/221396228791

[2015 Z Force 800 53/Trail EPS]

I use a free connector off the battery stubbed-out on the side of the bed to tie-in my maintainer/smart charger. Wire isn't large enough for jump starting but plenty fine for the charger. One of these but really 3' is plenty to get anywhere:

https://www.ebay.com/itm/164874199884?_trkparms=ispr%3D1&hash=item266344a34c:g:oo0AAOSwFShgpS77&amdata=enc%3AAQAGAAACoPYe5NmHp%252B2JMhMi7yxGiTJkPrKr5t53CooMSQt2orsSLY2M1Gjmuwt9c03vWNfiRtoRnOVsaixDgd5SMz7pI16V8VCFXAVwJNmD8PrMevYDuw2DERw9I3rGhgRo7DxRlXV0YIsymXaz9c8%252Ft%252BDADTyLLcmTfv0oN7TvpEgni%252FCx72G4j%252BA9EvirtJoXIEo3vfXjjXwP5lgP6gjkMiwnU%252FJ2QtH3Q2SebiuGK80pqNRW41K6zgfRtzfRkHxMESn7kTlzlMJg8%252BW77bzUZ9JeC9k2nkZxAkToRcGGJX%252BdTZ8YOhGgrGGubJcmJGhNohKJFTskvaxgcdIwikTB0%252FfgcnrmM5dl18km2ku0QiR2D8ceUIQauPHsT9kO0FCRsU2RCRdb%252B0xVO2iZdV46taG5m5Ch%252BE6f6%252FD12VDhZqRsrKONq2%252BDiEA1FioUYWv0DZ8nc%252BFGoA%252FBtKTQspJa7SmUlLjhLpuj%252BPJw0u4tpsJz9ws7TBkF5BtDQPNaP7Hn8cDbC2fSfD%252F2GjfkiMek%252FPSH8AKGUKx3hY7MZQnrJW%252Fvc7JhvrNJMI9IgiPh0Y3kyh2JQ67JHvMvCTpSITwrwl6rEqtHCKnk6FlQznaxfeGORjdVFOo%252FG2EazoMoS4EiWo%252FMKnV%252BmYpN8cPi28CUTTv2TXR4UTWtccNxoo8UG8z1wVl9Yp6OX2e%252BRWGbRFoEwmDn3UdDaYT7aRtu47NyGuA0AvrTVD%252Brs7qLn%252BpTEG%252B5Ow4%252Ba3s1M19he8lsQgxMzQuxCuRdZsoSUHeCx6FYFnHwtAGPrSPIgn4sE3MITF0DCgvesKbvehnLDq1aiwZhNp12aomGGQRcB4doPzAuW6MaG3Nc%252B8wpg9gagaRO9D90qxBUtO9LDU1GtSEXxlipUEoLAQ%253D%253D%7Campid%3APL_CLK%7Cclp%3A2334524

dealer I bought our machine from actually installed a wire with plug from battery to hook to battery charger.