I have a couple of problems with this last update.
Garibaldi ITTL is not the up-and-coming guerrilla leader he was IOTL: he has probably an official position in the RR (which one is a bit of a question, though. IOTL Garibaldi had the laurels of the gallant defense of the Roman Republic, and later on he had a visible participation in the war of 1859, but ITTL neither of these events happened: he still has his successes in Uruguay to give him some notoriety, but he has not really proved his mettle in Italy. He may certainly have been involved in the establishment of the army of the RR, but he has to confront with other career officers, Durando first of all, and I have a few doubts he'll find it easy to be accepted - IOTL he did not ask nor was offered a commission in the army). IMO, Garibaldi would be a politician first of all ITTL, sitting on the left of both the RR and the Confederal Parliament: the problem here is that he was neither a theoretician nor a great organizer, and probably he would get bored pretty soon (as it happened when he was elected to the Italian parliament IOTL). His strength is leadership of irregular troops, and probably he would end up doing exactly that: while on the political side he will bring up continuously the Southern Question (which ITTL has replaced the Roman Question of IOTL), he will also start recruiting and training Neapolitan expatriates and exiles and possibly infiltrating into the kingdom of Naples and trying to promote insurrections. Funding will not be a big issue, either by public subscriptions or by donations if not by Cavour's discretionary funds (there is no problem if Cavour has a plausible deniability, and the relations between the two men are going to be much better ITTL: the main issues which poisoned their relations IOTL - cession of Nice to France and refusal to integrate the Garibaldines in the Italian army - don't happen ITTL).
There is also the problem of finding a justification for kicking out Ferdinando or his son Francesco from his throne: the kingdom of Naples position had been sanctioned at the Conference of London of 1848, and some casus belli must be built up before an invasion. IMHO it will be not a huge problem to slowly build up a situation where the continuing existence of an independent kingdom of Naples becomes unviable. Ferdinando is not going to change his reactionary attitudes after seeing Austria kicked out of Northern Italy, the Pope fleeing Rome and himself loosing Sicily. He is not going to grant a Constitution, not even a conservative one, the expenses for the army and the navy will increase (even IOTL they were about 1/3 of the kingdom's revenues) and taxes will have to increase, since there are less revenues ITTL with the loss of Sicily. In the end (and the increased cost for loans, Naples is not an attractive place for foreign investors or bankers ITTL, Ferdinando will have to tax either the properties of the aristocracy or those of the church, probably both, alienating two theoretical pillars of his rule. I can see spontaneous insurrections starting within three-four years after the London Conference, also because there is now the comparison with the Italian Confederation, where political liberties are constitutionally guaranteed and economy is healthy if not yet booming. By mid 1850s the situation will be close to untenable, and that will be the moment for Garibaldi to make his move, entering the kingdom of Naples with his volunteers from the Latium border (and not landing in Calabria: why go there by sea and have to come back a long way toward Naples? Furthermore, the Italian Confederation needs a plausible fig leaf, and sending the navy to protect Garibaldi's landing in Calabria would be a bit too obvious). Once the volunteers are beyond the borders, and have proclaimed a full scale insurrection against the liberticide king, the Confederal army will come into play and enter Abruzzi on the east and Campania on the west (if one wants to go full hog, have Sicilian troops landing in Calabria too). Best case is if Naples' insurrection (which would not be too difficult to organize) is successful, and Garibaldi enters the city first , worst case if the insurrection is not completely successful and the Confederal army has to become involved.
In this scenario, Ferdinando dies in exile, and Francesco is not even crowned.
The other problem is why the pope tries to flee by land. That worked when he had to flee Rome, at least he had a place to reach within reasonable distance.
Where would he go now? On the mountains to live like an hermit? It would make more sense to leave Gaeta by sea, provided he has found a Catholic nation who is willing to take him as an exile (Spain, or maybe Portugal, since Austria is not going to take him in and I don't see him going in exile in Republican France).
