Questions on strength when permanently removing rear cross member behind tank.

Hi, been a while. I see sometimes the rear member behind the fuel tank is removed when doing conversions of the v6/v8 variety. Does this have any great bearing on structual strength of the whole car. Im planning a conversion that was going to involve me moving the member forward, (moving the fuel tank to the frunk), to give me more room in the enging bay. But I have seen the v8 conversion where it has been removed altogether. So im thinking of that option now. If it was questionable in terms or strength I have the option of a roll bar tied into the backend to help. What do you all think?
Thanks.