One other gotcha:
Your brakes are 12V. You *must* have a battery to run the breakaway system. Relying on a 24 to 12 converter may not be a real good idea for this part of things. One would have to do a bit of research into just what is "legal" state by state and country by country.
The same issue applies if trying to charge from your TV. You will need a 12 to 24 converter for that side of things. If you are going heavy lithium this may not be a concern. ( = doing significant charging from the TV may or may not be in your plans).
12V gizmos are made for the RV market. 24V stuff is made mainly for the boat market. Ask any boat owner what he thinks of the prices on the spares for his "treasure" .... do it with the kids out of range unless you want them to learn a lot of new words
Consider that you aren't just buying a fridge. The list of things in a modern trailer goes on for a while:
A/C (maybe two)
Vent fans (maybe two)
Power to computer(s)
Cable TV box from the campground people ....
Satellite TV box
and on and on and on .....
You can say that you will run most of this off of a 24V to 12V converter. Once you do that, you are right back to a 12V system. Since you have both 24 and 12V wiring, getting things crossed up ... yikes ....
Solar wise, you can run a 72V panel setup into 12V batteries or into 24V batteries. It's just a matter of how you wire this or that. Pick the right parts and it all works fine. There is no practical impact on the solar side of things *unless* you want it to be so.
What do you gain? Well, that depends ...
1) If you re-size the wire ( cut the weight in half) when you go to 24V, the voltage drop for a given power level will be same / same as it was at 12V. You will loose half the power you would have otherwise.
2) If you keep the same wire ( it's heavy but it's already in the trailer ) the voltage drop will be 1/2 of what it was ( current is half, drop is half).
What does this mean? If you had a loss of 1% in the wire at 12V, in case 1, you would save 0.5%. In case 2 you would save 0.75%. Yes you *can* measure these sort of losses with the right sort of test gear. Noticing a sub 1% change on a real RV in real use .... good luck.
If you want to set up to run your A/C off of your battery bank full time / mid summer then sure, 24V probably makes sense. The sort of solar and battery you would need is way past what you are talking about. How you would fit a few KW of solar on an AS .... no idea.
An AS has a *tiny* power system in it. Much of what you see here or there is targeting much larger systems. The "advantage" of higher voltage is mainly on a larger system.