Some thoughts about why sailing is different from [some] other sports.

55.3 definitely applies, so you can't apply pressure from your device outside the sheerline.  If the jib tack is right on the stem that means pretty much anywhere on the boom is going to be prohibited. What you can do depends on the fine detail of the setup. Suggest you post what the actual class is and class rules. On many modern Int Canoes, for instance, the jib boom projects beyond the tack to be used as a vang, and one may also attach lines or shock cord to act as a sort of reverse sheet.

Rob re: "were to luff sharply and hit the blue boat, the blue boat would protest under rule 16.1 and quite probably win in the protest room"

That's what I'm trying to say (in my typical awkward way) .. that a luff up breaking 16.1 would not be exonerated based upon Red's MR rights.

I'm not saying that Red is not entitled to MR .. she is. I'm arguing (for the sake of the argument ... wiling to be convinced otherwise)  that MR doesn't include luffing to HTW when that luff is not a component of a path to the mark that exists with MR. 

If I was to argue against that point I might argue the following ..

If Red luffs HTW and IF Blue passed HTW first , AND then when Red follows Red tacks such that Red is overlapped to windward of Blue as Red passes HTW (BOTH conditions required to keep MR contiguous) .. she will be the KC boat even if they are both tacking the same time, but Red's MR will change over from 18.2(a)(1) to 18.2(c) .. now being the windward/inside boat.  In that way, there is a feasible path that Red is never not entitled to MR as she tacks for the mark. 

That path though depends upon Blue passing HTW first.

Another argument against might be geometric.  Any time Red is in the 6-9 quad, when she luffs HTW she's shortening her distance to the mark (hypotenuse vs sine).  So that's "closer to" as in sailing past at some distance vs "to" the mark. 

Robert "My review of RRS 86.1(a) indicates no issues with this change."

An argument against that assertion might be that 86.1(a) forbids changes to rules of an appendix that changes Part 2 and Def's and that doing what you suggest .. in effect ... changes those Appx-rules by inserting a "however-clause" exception and then inserts the standard language.  

What I am saying is that it is more complicated than simply having a gravitational force component parallel to the local surface of the water.  Surfing, as a general phenomena, is defined and understood.  Where it isn't defined is in the RRS.  Unfortunately, this forum is not the place for the very long and very deep dive explaining the physics of surging, surfing, and planing.  But to me, the take away is that we need to understand the difference between surging, planing, and surfing and when each of these is possible to be able to properly interpret and apply RRS 42.