I am verry worried about the comments here.
I have always expected the parties to bring evidence to me. They have to bring the means of watching it. 
I have faught ahains those who said the rc may have a video or recording and i should obtain it. 
I am too busy with my responsability to all competitors, and save if i saw the incident feel the parties should provide their own evidence 
We can give more time to prepare if they request it. 
Yes i am a lawyer, we give decisions on the evidence presented, we do not find it. 
I have no problem at a vacaros event (a minority of events, where because ot the cost the owners do have resources and are used to collating information) saying (by notice not at the hearing) how they may obtain information. 
Perfect information shortens hearings. 
Seeking information helps one party and takes precious time. 
No we should wait for the information to be brought to us. 
As to the screen, yes if we have one the problem with events is the escalating costs. You are advocating increasing the cost base and pricing a jury out of events and clubs. 
We are appointed to finf facts from the evidence presented using our experience and we should stick to this and excell. 

Thanks very much John. I appreciate your efforts in replying in so much detail.

Our annual program includes a Pointscore Series (Pursuit format; scratch -> biased towards slower boats) run every fortnight ( 15 races per season), Championship (Yardsticks; 2 races each day; 14 per season) and Sprints (Yardstick, 3-5 races per day; 24 say races per season) => run in turn every other week.  (so C-P-S-P each month).
 
We'll be running our annual October Regatta (6 Divisions) , Hobie States, Spiral Nationals + the International Canoe World Titles this year so we'll be busy, and having lots of fun and enjoyable times out on the Bay!

As Race Secretary I want to apply a common entrant list and a common set of rules for our club races. (KISS).  We are transitioning from a Cox-Sprague system to low-point (Sailres) next season. We have a meeting next week to decide on the rules.

After much research and simulations and yours, and others kind feedback, my preferred approach is DNC= Starters+4. I thinks the committee could settle on DNC = [12] which is starters + 4 for our average fleet size of 8-10. There is a group who want to keep the regatta approach of Entrants + 1.
 
We'll see who 'wins' the debate. Interesting Times (pun intended)! 

Cheers and Thanks again for all the great feedback. 
PS many clubs face similar issues and so it is worth discussing it here.

Looks like several scoring systems allow for it.  You will find the instructions for how to do it on RacingRulesOfSailing.org here.

This may be relevant =>>>   https://www.racingrulesofsailing.org/posts/5752-minutes-advantage-formula-for-pursuit-races-based-on-phpf-hcp

Yup, Case 67 settles this explicitly in a W/L collision causing damage to a non-racing boat, it does not explicitly deal with the amount of damage caused being a conflict since in this case the rule 69 implications removes that discission.  I can't find a case where monetary damages were seen as a conflict of interest in the way it's implied in this discussion.  But the definitions are poor for several things including "damage" vs "major damage", and major damage isn't even a requirement, only that it may have caused major damage. so there is always room for interpretation.