Another option is to have the ballscrew beside the cross slide (on the tail stock side).
If you have space at the back of the machine, then you don't really lose anything much by doing what you have planned. Force is in the direction of the standoffs (I'd use a solid block if possible) so should be good.
My dodgy delrin ACME nut is mounted to the back of my cross slide (rather than under the middle like the original brass nut).
I'm still try to decide how to re-do mine.
7xCNC.com - CNC info for the minilathe (7x10, 7x12, 7x14, 7x16)