You might want to look at the carts/stands that the cowboy shooters use at matches for multiple guns, box for accessories, ammo, accoutraments, wheels to make it easy to move around, etc. Some are very well thought out and designed. Search on S.A.S.S. shooting carts or stands and see if there are styles and makers who have what you want.
I found many images, but don't know which ones are copyrighted, so can't post here, but they look very nce.