I want to conduct a grafting experiment, with multiple varieties of tomatoes/chillies/eggplants/tamarillos/tomatillos etc growing on the same plant.
Partly I want to grow annual tomatoes as perennials, and partly I just like experimenting.

Does anyone have suggestions for what may make suitable rootstock for my little experiment?

Desirable traits for my rootstock include:
Doesn't make the fruit toxic (so deadly nightshade is probably out unless I'm mistaken about the effects of grafting)
Being long-lived/perennial (able to grow for 10+ years would be nice but unlikely)
Strong, woody stem (to support the many different varieties)
Large size
Readily accept scions
Disease resistance