I agree with weight belt being easier to put on in the boat, thats why I would like to have the weight belt under the crotch strap. Do you wear a weight belt under the crotch strap now? To me needing to removing the crotch strap to remove a weight belt is problematic. It makes ditching in an emergency a lot more complicated with and I've also noticed how a full-ish wing wants to float away from you without a crotch strap on the surface, and I would imagine the same thing would happen underwater and make things difficult.
To me the "best" solution would be a weight belt or harness with ditchable pouches worn under the crotch strap, which would afford the best of both worlds, with being just a bit more bulky. However, the DUI harnesses are pricey and probably overkill for the amount of weight I'm talking about.
It seems like a $30 rubber belt and bolting some weights to the backplate may be good enough... If I can keep it to 8-10lbs that will be much easier to handle in the water.
I wear a weight belt under the crotch strap. I was initially nervous about it, because it does affect the ability to ditch the belt.
However, I am now comfortable with it for a variety of reasons. One is that I rig the BC waist strap like Jim L recommends with the loop of the crotch strap in front of the waist buckle. So when the harness waist buckle is popped open, then the crotch strap loop falls off and is unconstrained.
I have seen most recommendations to do it otherwise and have the crotch strap also retained by the buckle. That seemed dangerous and without any value for any kind of diving I want to do.
In addition, and because I am concerned about the crotch strap and weight belt issue, I have rigged the crotch strap loop with a fastex buckle. So I could choose to pop the fastex buckle, the crotch strap will fall away from the front and I don't need to open the waist strap on the BC harness at all.
I have experimented and generally if you decide to pop open the BC waist strap, the BCor BP/W is not going to fly off your body, it will just ride up a little and feel dorky.. not a big deal at all. If you do it at the surface and have a modest amount of air in the BC, the result is actually pretty minor.
In fact, think about what happens when you normally take off a Scuba unit with a BC on it at the surface. After removing the weight belt, you then pop open the waist strap and then slip your arms out or open a shoulder strap buckle. When you are doing this, is it a big problem for the few moments when you are wearing the BC unit with no waist strap attached? Not really.
If you are going to drop a weightbelt while at depth, think about the circumstances that would warrant that action....IF your BC was working and was inflated, then why would you be ditching lead? Answer is.. you probably wouldn't be dropping a belt.
IF your BC failed and you had to drop ballast (weight belt) to initiate an ascent, then almost by definition, your BC or Wing would be empty or containing little air; so even dropping the belt at depth is not going to be a big problem if you have to first open your harness waist strap - because the rig will be neutral or negative and will just sit on your back.
I can understand the idea of a weight belt being last on and first off, but in practice, you can be proficient in removing the weight belt by releasing the crotch strap. I am not a fan of pouches holding lead on the BP/W harness.
The thing to remember is that the proper way to remove a weight belt it NOT to pop the buckle and let it passively fall down when wearing scuba gear. It can be trapped on portions of the harness or get caught on a knife or even wrap around your foot for a few moments.
The proper technique is to open the buckle and then PULL the weightbelt forward and away from your body and when it is in front of you and clearly unentangled, to release it. If you are proficient and comfortable with that technique, then the prerequisite of releasing a crotch strap, is pretty inconsequential.