The best way to work put what you need is stay in it in your backyard if possible. From sleeping to cooking , lights, food storage, power etc that will give you the best idea. Take notes what you require as we all have different camping styles.
Mark
I have to agree with mark here, noone will know what you need more then yourself, test the setup one weekend, even if you take it just out of town for a test run.
We did our first trip 20mins drive from home, 1 night stay and we worked out everything we needed more of right then, first on the list was a new bed.
Inline filters are great but if you use good quality food grade hoses and clean taps you will never have much of an issue, it all comes down to taste.
A 15amp cable is good if you do a bit of caravan camping, not knowing KK very well myself, do they only use the 15amp plug to charge the battery?
If you have an older 15amp air-conditioner at home you can use that plug to power your camper, a good electrician will be able to wire one up in your shed/garage.
Enjoy your setup
Nick.