There is no reason to have a 5 gallon carboy that I can see, unless you are making wine in 5 gallon batches.
Unlike winemaking, there is no real reason to bulk age your beer. Just ferment in a bucket or a 6 gallon carboy, then bottle or keg it when it's done fermenting.
If you do your primary fermentation in a 5 gallon carboy, it will overflow almost immediately. That's a bad idea.
Plenty of home brewers do their primary fermentation in 6 gallon carboys. I'm not a fan of fermenting my beer in a carboy, but that's just personal taste.
I fermented in buckets for years, much how you likely ferment your wine now. Now I ferment in kegs, but that's another story and not an avenue you are likely to take.
You probably use a bucket or other large fermenter for your wine's primary fermentation, right? If so, just use one of them for your beer. It will work perfectly. Then, when the fermentation is complete and you think you need to rack to a carboy, STOP... and simply bottle it up.