I would always err on the heavy side with anchors, most places you put the hook in are fine then go to one spot and the anchor drags, a bigger anchor helps plus a good length of chain 1.5 x boat length is a good guide. Then loads of rode, when the anchor doesn't want to hold 5 x depth is often needed particularly when there are a few waves around creating some snatch. Your setup sounds fine except I would want a longer rode, there are a lot of 30m marks round here so that would mean 150m. I think up to a 10kg anchor is quite managable on the Alderney ring, any heavier and it gets very hard work to lift over the side with the chain, for me anyway. On my 10m boat I use 15kg anchor, 16m of 8mm chain, 200m of rode. Very happy with that setup except would like another 60m of rode for some mid channel anchoring spots. I use a windlass with an Alderney ring as a backup. The idea of an anchoring guide sounds good. Fisherman's requirements for anchoring round here are far from typical with our depth of water and speed of tides. Non boat anglers have no clue what is needed for anchoring in 30m of water in 2 knots of tide.