In crowded situations... you should practice the 1 tatami rule.
ie... throw uke down in your 1 tatami space. I think this was once discussed some time back about injuries/fatalities in Aikido. And someone was paralysed because of another person falling on her/him. Its not a good way to end your aikido career and ain't smart either to live with it.
If nage is insistent in throwing you around hard/fast where you can also become a nuisance to someone else, its your duty as uke to point him the error of his ways. Kaiten nage to a brick wall is SOP. :P