How do you avoid overloading mechanical engines?

Following a drift in this thread (with apologies to Beau about that), I am now following CaptPKilbride suggestion to start a new specific thread on this subject.

The debate was about how to avoid overloading mechanical engines, particularly in a boat where for some reason (like trimmable Arneson surface drives) it is relatively easy to run her above normal propeller demand load, also while cruising under the max rated RPM.
I wouldn't focus on Arnesons though, because even if they surely are more prone to demand high engine loads compared to shafts, overload conditions can happen also with shafts, regardless of the reason (wrong or dirty props, fouled hull, excess weight onboard, whatever).

CaptPKilbride explained me that his way to avoid such risk is, after fitting very accurate digital tachs, to shortly run the boat at WOT in the specific conditions (load, trim, etc) he wants to cruise in.
If the boat can reach the rated max RPM, all is well and good.
If she can't, he knows there's something to be adjusted.

Now, I don't think there's anything wrong in his logic, and I have zero objections to it.
But I believe that if the boat is fitted with EGT gauges, that is an equally effective way of spotting an excessive load as soon as it happens, with no need to run the boat at WOT.
In fact, AFAIK, the very first consequence of overfueling the engines, at any RPM, is a noticeable and immediate EGT increase.
And by immediate, I mean it - in a matter of a few seconds.
In other words, as long as EGT remains close to its typical range (which can be easily recorder upon a seatrial in ideal conditions), by definition there is no engine overload to speak of.

So, over to you guys, what do you think?
Is one approach better than the other (and if so, which and why), or are both good enough?
Besides, are you aware of any other tricks, maybe?

Of course, I'm happy to be corrected by CaptPKilbride if in the above summary of his approach I misunderstood anything.

Not yet, also because my boat doesn’t have any EGT probes/gauges – hence my interest to fit them.
But let me add a couple of comments on that:

Firstly, one thing I always noticed while helming boats powered by electronically controlled engines (whose displays can tell you just about anything, as you surely noticed with your new Böning MMDS monitors) is that there is a remarkable correlation between EGT and load.
Normally, they go up and down depending mostly on RPM, but for instance on a long range cruiser with almost 3k gallons of fuel tankage, I did see a difference in both load and EGT before/after refilling.
Or in other words, we used to run at the same EGT/load after refill, as we did with empty tanks, but at a lower RPM, hence speed.
Not a night and day difference of course, but noticeable. Half a knot or so.

Secondly, the person from which I learnt the theory that I explained in my OP used to be a technical manager at Cummins, where he was also a member of their design team. On Boatdiesel, where he’s a moderator, he’s known as the “diesel engine bible”.
He literally used to say that he would be happy to run a diesel engine based on EGT alone, rather than on any other instrument.

As an aside, it’s worth mentioning a partial exception to the EGT/load relationship, and that’s with planning boats with u/w exhaust.
In fact, EGT doesn’t depend only on load, but also on backpressure.
And with u/w exhaust, backpressure can progressively increase before the boat is steadily on the plane, and then reduce slightly, when the speed begins to exploit the scavenging effect on u/w exhaust.
But that’s easy to check and keep into account, by making an EGT baseline as BRyachts suggested.

I agree that it's pretty rare, but not impossible.
I've seen straight shaft boats unable to go on the plane due to heavily fouled bottom (both hull and u/w gear).
Just run such boat for a while with the throttles hammered, and I bet you will see EGT skyrocketing in no time.

Then again, if you would argue that it doesn't take any EGT gauge to understand that such boat desperately needs a good clean, I'm not disagreeing, of course!

I mentioned electronic engines because only with them you can monitor the load.
And in my experience with them, the higher the load, the higher the EGT.
Consequently, if you follow the same reasoning backward, whenever you have higher EGT (which you can monitor also with mechanical engines, as opposed to load) it's safe to assume that it's due to higher load.

The fact that you can't see the load with mechanical engines is a red herring, because the logic actually remains exactly the same, and it is indeed possible to overload also electronically controlled engines.
In this respect, I agree that the max RPM check is as much a good practice as it is with mechanical engines.

OTOH, keeping an eye on EGT (possibly with the support of alarm set points, as BRyachts suggested) is in my opinion equally effective if not even better, and doesn't require spooling up at WOT every time you want to adjust the drives setting for whatever reason.

If so, maybe Norseman already used the N2k interface to feed the Floscan instrument above the callsign?

Ok, that's irrelevant vs. your interest to fit a pyro sensor, anyway.
I believe the point CaptRaplh was making is that by fitting a N2K sensor you might be able to display EGT directly on the Garmin plotter, with no need to install a dedicated instrument.