It depends on the meaning of the word "STOCK" (you are going to hate this answer)
Chances are you define the word "Stock" much like Hobie 16 world.... Basically, if you did not buy it from the factory... its not stock... Oh... and the factory can change things any time they want..... so by definition.... its STOCK.
Maybe, you are a bit more open minded.... you can add a different bugee set up for your trap lines, arguably violating the rule but not the spirit of the rule..... and so it starts.
SCHRS ratings are not going to fuss with how you run your trap lines or what type of running rigging (high tech line) you use. So.... STOCK is a meaningless term for a Hobie 16 rating.
The A class has no concept of stock... They just have a measurement rule box that you must fit in. What is STOCK for an F18? .... do decksweeper rigs count as STOCK? (rhetorical question only)
The T class has had a number of rule sets over the years... The current rule set tried to make it as much like a SMOD one design for ISAF Olympic selection trials after cats were booted. The fleet entered a one design Tornado class in the selection trials..
Would you use the word "STOCK" Tornado to describe the Lovell and Ogletree's Tornado in the China Olympics sporting the only code zero geneker in the fleet going up wind at the start of race 1? By rules at the time.... it was a STOCK Tornado.... QED!.... Of course, what people really meant was.... Was it FAIR.? Bottom line.... ISAF demanded changes in the Rules defining "STOCK" after the Olympics. (The USA Tornado finished dead last... so they shot themselves in their own foot.... so... answer to the ? fair? ... would be Yes it was!@)
My advice would be.... get a judge involved and clearly define the rule set for the race. Make it crystal clear what the standard for measurement compliance will be and put the responsibility on the owners to meet it. NOBODY wins when you half butt this and the OA's lack of rigor opens a door for debate after the fact... That's when you get the BS started that xxx is a cheater boat and everyone just walks away.
so..... maybe you don't want to use the word "Stock" in the rule set!
Fair... is an opinion and likely grounded on where you stand. Not a good word to use in the rule set either.
The other pitfall is using the term "Class legal" without careful thought. Are the numerous Class rules comparable? Is it FAIR for that particular race to run using a Class Rule standard... Hell.... You can't even find a collection of class rules for some classes that might show up..... Why would a fleet of 1 boat in a class need a lot of rules??
Bottom line....think carefully about what you want.
This is all good advice, but I'm not sure the organizers will take this to heart. If they want the race to continue being successful, and down the road, want the Worrell 1000 to be successful, they need to beef up the rules and actually have an international jury available to take protests. Otherwise you get into all sorts of issues (cough couch Cape Canaveral exclusion zone). The lack of proper management in these areas is a prime reason why I haven't shown up to do the race, among others including wear and tear on a boat that spends a good deal of time buoy racing, plus the usual excuses of time.
Mark I realize your question is rhetorical, but for the rest of the world, the F18 is also a measurement box rule boat...its a much tighter box than the A but things like decksweepers are legal per the rules and at this point are here to stay. Are they faster, well, upwind yes, downwind maybe not. Will the F18 SCHRS rating change as a result? No. Will every one else's SCHRS rating potentially change as a result? Yes, as the benchmark boat is the F18 and if it gets faster then the boats around it have to change, that is simply a result of how the formula works, and it may confuse many sailors.
Then you have classes with ambiguous class rules as mentioned above. SCHRS I think handles that in a good way with a measurement based rule, but it would help if sail areas and mast areas are prescribed by the builders for granting of an initial rating.