I use compression sacks that are not dry bags, put them in the Ortliebs. Instead of sizing the compression sack to the volume of a packed sleeping bag, I sized it to the space that each compression sack fills in the Ortliebs. I put one in each Backroller, oriented horizontally on top of everything else. The diameter of the compression sack is the same as the thickness of a packed Ortlieb Backroller. Sleeping bag and some clothing go in one, rest of clothing in the other. (Rain clothing packed where handy, not in compression sacks.)

If it will be a cold weather trip, some clothing won't go into those two compression sacks, on such trips I bring a bigger sleeping bag and more clothing. On those trips, put excess clothing in plain stuff sack. Nothing else really benefits as much from a compression sack as much as clothing and sleeping bag.

Also use one small drybag for electronics, medicine, spare batteries, charger, etc. Have another small drybag for camera, camera is normally not in the drybag but drybag is handy for sudden rain. Nothing else really needs to stay dry so nothing else goes into a drybag.