Leveling side to side method from seasoned campers

Thanks for all the replies. I figured this would become a good thread. I'm leaning towards those Andersen style ramps. I need to look at my wheels and check the spacing. I would much rather have the aluminium ones ( $70 each!)but wouldn't want to cut them . They look like they might have a little traction compared to the smooth Andersen ones. some one said they tried attaching gritty paper with no luck. I'm not looking for perfect but would like close.