I think we saw some of these Gerogetown units a recent RV show, not sure what models. I believe you may even have a large door opening at the rear of the RV too. Our unit (330TS model) like a lot of the units where the bedroom has a slide for the bed, do not have anywhere near this large open space you're referring to. I think that's because of the machinery and tracks to make the slide work. In your case (300S model) where there is NO slide in the bedroom, there is this large space you refer to, which at first appears like a bonus because of the openess. However, I never investigated enough to see what/where to secure items like you mention. You also have good reason to secure any items in here because anything located behind the rear axle will tend to bounce around more than other locations along the chassis. I know.....because I drive School Buses, and you should see the kids bounce in the seats at the back along the bumpy roads! Have you been able to crawl underneath the chassis and see if there's clear access to the floor and install some of your own eyelets into the floor to fasten straps, bungee cords or whatever?