Tape is fine it'd not a large tank and it's not holding water so clamps probably are overkill
A 1/16+ spacing is fine , main thing is glass doesn't touch glass very important ok , measure your panels and you'll be able to figure out the spacing allowed when it was cut
For home made spacer cut a small 1x8" x 1x8" piece of vinyl hosing or similar make sure it's flat is all
one on top one on bottom