I would bypass the V15 and for straight to a V18 for hatchlings V18 it will allow you to grow snake up until they reach about 600+ grams. (That will be one less upgrade)
Once they are ready to upgrade they can go into a V35 however a normal V35 not the short one, the short one will only allow you to keep BP up to about 800 grams. (So skip the V35 short)
Now for bigger females I recommend V70.
Vision tubs are thicker, stronger and have no groves making cleaning a lot easier.