Random thoughts, in no particular order:
I agree with GL - crew weight is not as critical on a DS as you might be used to on a lighter boat. Weight DISTRIBUTION, on the other hand, is very important. You want the boat to be level on her lines (sit amidships) for most points of sail, and weight at the back running downwind. That being said (writ), I'm also not currently a one-design racer and it was Hobie-Cats back in the day, a whole different ballgame. For my usual noodling around the lake, all I want is a crew member who will shift him/herself to where I ask... usually all the way forward to the lip of the cuddy and outboard. For what it's worth, the boat's natural balance point is pretty much right under the logo on the cuddy. I know from when I hoisted her up and flipped her for painting. However, depending on conditions she'll have more buoyancy fore or aft of that point. I think the biggest "learning curve" for an experienced sailor is getting used to the balance between her fine bows and flared/planing aft parts.. scooting your combined weight a few inches fore or aft makes a big difference, moreso than total weight, at least IMHO. I also sail single-handed most of the time, and for light-air days it's ideal. On heavier-air days (say above 15 knots), I start to really want a crew-mate, if only for the "live ballast," not having to reef and being able to properly sail thru the gusts. Having sailed with several different crew, I'd say that someone about 1/2 my weight is ideal (I'm 260 lbs) - I can move them around to offset ME (Hey, I have to free the damn traveller, can you scoot a foot forward while I do it?), and the boat is still lively. I'll admit that when sailing with my son (also a big guy) or two crew aboard, the boat can get a bit sluggish. Weight starts making a difference in light airs, say under 5-6 knots true. Over here on the East Coast, where the wind often dies down suddenly, the Old-Timers (Chesapeake Log Canoes, Delaware Tuck-ups, Sandbaggers, etc) actually would send crew overboard in light air! Let them swim ashore or to the committee boat. I miss the old days....
And I have to ask - what is this magical place where you sail that you can pick and choose your crew by weight? Over here, I'm happy if my crew show up within and hour or two of when we'd agreed to meet up, and if they are passably sober when/if they do show up at all. It's pure gravy if they can pull on a rope and move themselves to where I ask when we tack. And I'm absolutely playing with house money if they know how to "hand, reef, and steer," let alone call out puffs and traffic for me. Anyway, even if I lived in this Sailing Shangri-La of yours, I think I'd still value a skillful "salty" crew over one who has a "correct target weight." Weight can be adjusted (within reason).... there's the old wet wool sweater trick for more ballast outboard, and if too heavy (for the conditions), throw crew overboard!
Just kidding, of course, and here's to fair winds and a handy, smart crew!