The little short ones were meant to be put up on a step, like mine is on step that is actually the black tank underneath hidden by the bathroom flooring of course. If they put the short little one on the floor, then I feel for you, as they are toddler height.
YouTube has several videos on how to install an RV toilet.
Probably too late to mention it now.. but that could have been a bargaining chip when buying the RV, asking the dealer to put a real toilet at the proper height in there.