8289ws storage compartment opening sizes:
Right side (Entry) storage compartment door opening is 18" W x 23.5" H...floor to overhead plumbing clearance is approx. 17.5"
Left side (Hook-ups, WH, Ext. Shwr) storage compartment door opening is 38" W x 23.5" H...floor to overhead plumbing clearance is approx. 18.5" (15.5" to shower trap).
FYI: 20 3/8" from floor to bottom of aluminum joists throughout compartment.
At WalMart I found Sterlite 27qt. ClearView Latch storage bins
and 15qt ClearView Latch storage bins (double stacked are same height as 27qt).
They're clear so you can see what's in them and they fit perfectly along the front of the compartment clearing the shower trap, leaving plenty of room to the rear for other bulky items.
Hope this helps!