They look great, I think your bases are fine as-is. On my own bases I fill the stand/base gap with a very fine sand first.
Now that you've pointed it out, I do see the sticker edges clearly (though on table would be no issue). It may be worthwhile trying to go around the banner with thinned down 'liquid green stuff' (or similar thick-drying paint). It's my usual go-to thing for blending away small nicks and ledges.