Thou asketh, thou shallst receive

What it looks like from the waterside:

The "operator experience":

Preparations, including firing up and raising steam, warming through the engine and removing excess condensate from the oil collector, takes about 10 minutes.
Max burner time on one gas filling is about 50 minutes (60 grammes of LPG), but it works slightly better with a 30~35 minute fill (around 40 grammes).
The boat needs a water supply every 20 or so minutes otherwise the feedpump runs dry and you will need to cool down the boiler to prime it if that happens.
But with roughly every half hour a 2 minute "out of the water" pittstop for fuel, condensate removal and water refill the boat can be kept in operation until the receiver battery is depleted OR the cylinder lubricator is empty, which I estimate to be about 2 hours..
In between pittstops it is advisable to every now and then check waterlevel in the feedwater tank, but with a bit sensible powermanagement, 30 minutes is possible.

Such a pittstop consistst of raising steam pressure, (normally automatically controlled at 1,2~1,5 bar or 10~15psi) manually up to about 2 bar (30 psi) before landing, at landing closing off the main steam valve, kill the burner and stop the feedpump.
Blow off gastank and refill, empty the oil separator, fill up the feed tank, relight the burner, open steam valve, and on low steam run the engine until the condensate in the engine is out. empty the separator once more, and the boat is ready to go again. If you have your equipment ready and your sequence of actions laid out, it can be done in about 2 minutes if nobody of the onlookers cause distraction (which they invariably will do ).

It's not for everybody, but for me, the rather hands on intensity of operating such a steamplant is the appeal of it all... Because running the boat up and down the pond in itself is not all that exciting. The more traffic on the pond, the more fun it becomes, as manouvering the engine is less straightforward than an electric drive.

By the way, funny you say that... This type of boat originally was used in the German Bight area as an "Inselversorger" or island supplier, and as such did indeed "haul the mail", quite literally...