Euro around the top will be fine.
If you don’t want to do full euro you could just do three pieces on top front to back. Left, right and center.
For the bottom you can do internal but that would require a re-seal to do properly.
You could add some external glass at the bottom on the sides front to back and even down the sides.
I’ve repaired several tanks for a LFS this way.
It’s not the best looking but it does work well.
I’ve also set up tanks with no frame on the bottom without any extra bracing.
Either way without a bottom frame you need to make sure the tank is leveled properly and put at least 1/2 inch foam underneath
It also needs to be fully supported.
A stand made for a framed tank will not work.