You could get an inflatable bathtub. They fill up easily and enable your baby to sit comfortably while you scrub them.

My baby was 27 lbs at 8 months, which is a lot of wet, soapy baby to hold in the shower. So we have opted to have one of these tubs on-hand for scenarios like this.

There are also some folding/collapsible tub options now. Not sure which would take up less space/weight in checked baggage.