back on the dials for the downwind turn
probably overstates it
a bit but on the other hand when 'visual' at the end of an IAL procedure in anything approaching min required vis you will be relying on your instrument scan for performance information while also scanning outside to fine tune the circling.
Use 1% of your ground speed as a prompt for starting the 90 degree turn - @130kts 1.3nm - so for a circling area of 2.7nm start your turn at 4 DME.
Look for things 'associated with the approach threshold' - maybe a river bend, house, road, clump of trees to help you fine tune the turn onto finals IF you cannot see the runway on very late downwind.
Think about how high you are AGL and how far from the landing threshold you would be on a straight in approach
at that altitude. If you're around 400AGL then that would equate to about 1.3nm to touchdown on a straight in. If you are circling at 2.7nm you can certainly afford to turn base level, and will probably HAVE to if you're not to end up dangerously low, and should have plenty of time to sight the approach threshold and line up, using your little landmarks if needed, before descending from circling altitude. If there is an obstacle that puts you up around 800AGL (400' above the highest obstacle in the circling area) then you would be something like 2.6nm out on a straight in so can't afford to dick around too much before descending but you can CERTAINLY afford to START the base turn level while picking up on your cues and then descend in the turn.