Remove level limit from XP from construction?

The campaign section states:
A character receive 1 XP per 2gp spent constructing the stronghold (castle, sanctum, hideout, etc.) he uses to attract his followers. The XP is earned when the character’s followers arrive. If the character ever loses the stronghold, however, the character loses the XP earned from its construction. This may result in the loss of class levels. The character can regain the lost XP by re-taking the stronghold intact. If the stronghold is partially destroyed when re-captured, the character re-gains XP equal to its reduced value.
I like the part about needing to regain possession of the stronghold. However, by tying this to followers, it means that it only becomes meaningful for characters who are high enough level to attract followers. I don’t think this is necessary. In the Age of Worms campaign Greg and I played, one of the things we had a lot of fun doing at low levels was fixing up a farmhouse we’d taken over after kicking out an owlbear who lived there. Well before we were at the level where we had followers, we spent several thousand GP putting walls on this place, fortifying the roof, etc., etc.
Would there be undesirable consequences from allowing characters of any level to gain 1 XP from every 2 GP spent on construction? In a saltbox game - or one that starts on a tiny island, like Erol Otus’s adventure at North Texas RPG Con this year - I can also see awarding XP for characters who spend on building a boat to be a similar home base for themselves or the party.

I’m busily converting my saltbox rules, and was wondering something very similar. Namely, once I started to use the domain rules to track mutinies, I started sketching out a sea-borne domain path as well (Deckhand Captain Commodore?). One of the key questions is at what level a character has enough gravity to command a ship. Unlike a barn, running a ship could mean commanding a couple dozen men or more- probably not a first level activity. I’m working my way backwards from the retainers-as-vassals rules and the descriptions of pirate ships to sort it out.
In the saltbox rules now, every ship has either a 5th or 7th level captain, and a 4th fighter beyond that for every 30 men. This makes sense to me (to have a captain and an officer for every 30 men), and is an approach that would dovetail nicely here: You get XP from constructing a “stronghold” if you are of sufficient level to command its population. A first or second level character’s hold on a crew of 30 would be tenuous as best, but at 5th level, with a 4th level retainer, you could probably swing it.

I think this could be a great low to mid level addition to the game. If its one thing players like to do, its make something their own. I would encourage this option for the game. However, there are two downsides about losing XP if the stronghold is lost. First, players have to track how much is invested in case it is ever lost - this seems like a bit of a pain to track (and can easily be lost). Second, rules would have to be implemented to account for the transition from “home base” building to domain building since at some point the game transitions to domains and not the home base.
As for your original question about XP, I really couldn’t answer that without testing it out. Sorry!

Might another mechanic be better served than XP to track loss of strongholds, or in the case of saltboxes, a “vote of no confidence” in the case of a mutiny? Experience seems to me to be something you can never lose once you attain a certain level (with the exception of level-drains, but that’s more associated with losing life essence). Perhaps upon attaining a Conqueror level rank, a PC gets a Glory/Renown/Command type statistic which can vary based on winning or losing domains, followers, and land?

In some ways, this rule re: loss of xp indicates that level is more than a metaphor for ability/expertise in ACKS- it suggests that it incorporates both that and glory/renown. That said, you could always house-rule it to suggest that you can’t go down in level, but you can go into an “xp debt” for the level you’re at. That would also give you a way to transition from “home base” to “domain”- you lose the xp from your old home base, and gain from building the new stronghold.

I have removed the level limit from building a stronghold. Instead, all that is required is that the stronghold be used to secure a domain.
The new rule is: “A character receives 1 XP per 2gp spent constructing a stronghold (castle, sanctum, etc.) used to secure a domain. The XP is earned when the stronghold is completed.”
This means that a character doesn’t get XP for just random, pointless building projects, but if he uses it to attract peasants, staff with a garrison, etc. (even if it’s a tiny one-square mile domain), he’ll get XP for it.