There are twelve short encounter/adventures that you could place near Hirot --
<horn toot> Try
In the Prison of the Squid Sorcerer.
Mermaids of Yuggoth -- whereby the adventurers acquire a small house as a base of operations and then realize its "haunted" over a period of several weeks....
The Long Sleep -- whereby the adventurers are drawn to investigate why the local gravedigger has disappeared... low level...
Slaves of the Visitants -- whereby the adventurers discover a cairn where creatures from another dimension are trying to take hold... </horn toot>
In addition to the Appendix N Toolkit, there are the Purple Sorcerer adventures -- just need a nearby swamp. There's also three short adventures from Purple Duck that are great for a "next steps" adventuring (<further horn toot>One of them is mine...</further horn toot>
I found that Doom meshed right into Sailors on the Starless Sea and People of the Pit -- my players based themselves in Hirot for both of these adventures.