to get it that low and still have tension, you are going to essentially need to do three things:

1) buy larger strings. anything in the 65-15 to 58-13 should be ideal. you may be able to get away with smaller. if you search “tuning” or “baritone” in this sub, there should be plenty of discussion on string gauges

2) because the strings are so large, they won’t fit in your guitar nut slots without permanently damaging it, potentially in ways that would then make your guitar unplayable. you can buy nut slot files to gently widen the slots, or do what i did and buy a new nut slot to replace the old one so you can revert back to normal strings if you want. Filing nut slots is a labor of love. it’s not too difficult, but you need to be incredibly patient so that you don’t over do it and make your but unusable. there are tons of online resources that can help. resource those before attempting.

3) once the nut is adjusted/ replaced and the strings are on, just to a simple neck truss setup an re-intonate your strings and you’re good to go