Someone asked why one would have any more overhang than the minimum for a bow roller. I would suggest there is a balance between the cantilever of the overhang and the amount of expected swing of the proposed anchor to be used. Insufficient projection means the anchor will likely bang on the hull as the boat bobs while retrieving or launching. Too much overhang results in excessive loading due to cantilevering on the fittings. Like everything is sailing, its a balancing act.
Our forward roller is about 8" fwd of the bow, the second on the port side of the bow about 5-6" - either anchor can be launched independent of the other. On our A-37 Sunstone, when cruising, we carry a primary 45lb CQR in the Stb Bow Roller and a 33lb Bruce in the Port bow roller. We have large flange cheeks on the roller to keep the anchor, chain & rodes captive so it can't jump off the roller and chew the hull. It is a custom design drawn by me and fabricated by Klacko Spars in Oakville Ontario Canada. The cost was not much more than a pair of off the shelf robust rollers. In polished stainless, it looks quite nice and we have had a lot of compliments - it does not detract from the aesthetics of the bow and in fact compliments it.
One more suggestion if you don't mind.
The bow roller should only be loaded when setting and retrieving the anchor - the rope rode if used should, while at anchor be run through the bow chocks. If using all chain, a rope with a proper chain hook should be run from your bow cleat, through the chocks and hooked on to the chain above the water with the chain let out so it forms a loop of chain - this takes the shock loading out of the system.
We carry 200' 5/16 High Test chain (Group 40) on Sunstone and use a 50' 1/2 snubber line with a high test 5/16 chain hook - 95% of the time we only use the first 6 -10 feet of the snubber. The rope shock absorber runs through the bow chocks. The extra 40' is in the event you need to veer more scope, you can just let out the chain and rope snubber to increase your ratio without having to haul in and then disconnect the chain hook. This is a blessing at night when you are tired as it keeps the likelihood of errors to a minimum when you are tired and visibility sucks ;)
If you have a windlass or capstan it should never be left loaded under tension at anchor - use the snubber line. Your gears and bearings will last so much longer.