Being able to adjust the jaw like this does allow the helmet to fit on just about anybody, but that gapping may be too annoying for you
If hes throwing larger lures or using a heavier reel, like a 300 or 400 size, hell step it up to a Medium Heavy in the same length range
Or, we use the water-repellant cube for toiletries, packed into our gym duffel
AGVs have been a little hit and miss for me, but the AGV Tourmodular felt very good from the off, with no pressure points on the head, despite fitting snugly
What we are waiting for is a Shoei, an Arai, a Schuberth, or indeed any one of the major manufacturers, to produce a serious retro helmet that fits well, safely and comfortably