I too have had a group of 6 tiger barbs that generally only bothered each other.
but neons are small, so are cherry barbs. that was my concern.
I agree with the others though.
if you are still doing research, the research should tell you to invest in a larger tank now, rather than delay the inevitable in a short time anyway.
that way you would also be able to put more fish in it, something closer to your list.
saves you the trouble of upgrading when you could do it right from the beginning.
but neons are small, so are cherry barbs. that was my concern.
I agree with the others though.
if you are still doing research, the research should tell you to invest in a larger tank now, rather than delay the inevitable in a short time anyway.
that way you would also be able to put more fish in it, something closer to your list.
saves you the trouble of upgrading when you could do it right from the beginning.