How about something like photos.google.com? They have infinite(well, all history) scroll, but it is done perfectly. The scrollbar size doesn't change and you ar

How about something like photos.google.com? They have infinite(well, all history) scroll, but it is done perfectly. The scrollbar size doesn't change and you are given enough feedback to scroll directly to the part you want. Similar is google maps. If you make it a large canvas where the missing data is paged in then it becomes quite natural.