if the show is big enough, you will be showing against other beefmasters, so you shouldn't be at a breed disadvantage.
at some shows, after the individual breeds (or classifications) show, there will be a drive for overall champion. this is what you may have been warned about regarding beefmasters not showing well because they don't have enough hair.
as for whether or not a judge likes beefmasters, that all depends on the judge. of course, they all have their preferences, but a good judge will put those personal preferences aside & pick the best quality heifer.
you also mentioned that it's a beefmaster cross calf. you might want to check on the beefmaster rules for showing to make sure that a cross calf is eligible.