Hello Adza,
Understandably you're a bit anxious about something like this but in my experience as long as your courteous and have your ducks in a line a Ramp Check is very painless.
For your Weather/Notams it's not a particularly strenuous or costly task just to print these out quickly before you head off so I'd suggest just doing it. If you're just doing a scenic then you only need for one destination and it shouldn't take more than an A4 piece of paper to have this onhand. With the ERSA I believe you can just download the relevant ones online and print them out instead of purchasing an entire ERSA.
Aeronautical Information Package (AIP) | Airservices
For Fuel, CASA have this handy little A5 size laminated Fuel Log that they hand out for free, head into your local CASA office if you have one and ask them for one or you can get them online for free. A quick scribble each time with a marker you can wipe off after each flight and you're free and clear and they'll probably be impressed you're using their little tool!
SP088 - Flight planning kit ? Civil Aviation Safety Authority Australia
Appropriate Charts, just grab a local WAC to go with your EFB and a VTC if there is one that covers you and you'll be just fine, it's only a few beers worth and once again you never know if you might need it one day. Keep in mind you might know the area but someone who doesn't may be referencing a WAC chart to tell you where they are and the name of a location there may be different to what's on the Chart. As Sunfish said, keep it within arm reach as well.
Weight and Balance is just the way you described it and is what I did for both Skydiving and as a backup for Charter/Scenic Flight, just have one done up that represents worst case scenarios, maybe 2 or 3 that you can think of to demonstrate you know the limits of your aircraft.
With your logbook I'm not entirely certain about this, I am pretty sure they allow you a certain amount of time to bring this in to be checked but it's been a little while since I've been back in Aus and if you get a snarky FOI he may just decide to not believe you and you could be grounded, once again I don't particularly see the issue with taking your Logbook with you and if you're using the same Aircraft all the time then you'll have evidence of your flights in the Tech/Maintenance Log and that should suffice I'd say.
Doing the above will take all of about 5-10mins and give you piece of mind, if you have an FOI that likes to visit your field regularly and this is what has you concerned then after doing it a few times he may just get used to you and decide that you're not worth the effort of annoying each time as well!