Would this work? (from https://forums.autodesk.com/t5/visual-lisp-autolisp-and-general/mtext-background-mask-settings-lisp/td-p/5998702)
Add this in after you have created each mtext or go back to the link above and do it by selection set
(setq dxf_ent (entget (entlast))
(entmod (append dxf_ent '((90 . 1) (63 . 8) (45 . 1.1) (441 . 0))))
Yes, double click inside the viewport to make it active and then work on your drawing there. As for good practice, I do most of my work inside the viewports, but someone else might do most of their work in model space. It really depends on what you're working on.