How to do XP for the Forest Gate was a bit of a puzzle, at first. This was an exploration-heavy, potentially combat-heavy, loot-light area that required significant effort to unravel.
It was designed that way. Nothing the PCs could do was going to increase the amount of per-session loot except perhaps for finding the staff right away and then finishing the whole deal in one or two sessions.
What I basically did was allow for an inverted system of XP for sessions. If the PCs found enough salable loot in a session to satisfy their loot requirements, I used the 4/2/0 plus 1 or 2 for exploration setup. If the PCs mostly explored (since there wasn't a lot of loot to find) they received 4/2/0 for exploration and 1 or 2 for loot.
This was an exception for a specific type of adventure - this isn't precedent for sessions spent exploring instead of looting getting exploration-based XP. There simply was almost no loot in the entire place, so it wasn't fair as a GM to judge the PCs based on that. In a place like Felltower, where there is a lot of loot (albeit often hidden and/or guarded) the PCs get judged on the ability to extract that loot.
XP were the same for everyone:
FGI on 9/1/2019 - 10+ explored locations = 4 xp, 0 xp for loot = 4 xp
FG2 on 9./15/2019 - >1 but <10 explored locations = 2 xp, 0 xp for loot = 2 xp
FG3 on 10/6/2019 - 10+ explored locations = 4 xp, 0 xp for loot = 4 xp
FG4 on 10/20/2019 - >1 but <10 explored locations = 1 xp, 4 xp for loot, 1 xp for clearing out the Garden of Trent Oakheart = 6 xp
FG1 was exploration-based.
FG2 was exploration-based. The session was spent, mostly, on talking to vegepygmies and then exhaustively trying to defeat the evil tree.
FG3 was exploration-based.
FG4 was loot-based.
MVP for the sessions were:
III: Aldwyn's player (for playing Dryst and making pie)
Hopefully this is a useful glimpse into how I did xp using a loot-based XP system in a deliberately exploration-and-puzzle based adventure.