removing sills seems to be common today, where the posts are instead bolted down to the foundation below some how.
But I've never been a fan. I'd sooner put in a framed floor. It's not that hard to make a wood floor strong enough to support a truck, lots of bans around here have them.

How far apart are the purlins?
It is very common practice on granaries in the southern Germanic areas to have a purlin roof, and it's also common in Sweden. The granaries of Switzerland and Austria are very closely related to the log houses of Norway and Sweden. I've seen lots of granaries in the Canton of Bern framed like this -the purlins supported only by the walls and spaced about 4 feet apart. This supports a board roof, onto which wood shingles are nailed (today its often ceramic tiles)