ᐅ Secure 3mm MDF panels together temporarily

Due to slight unevenness in the floorboards, I would like to lay 3 mm MDF panels before installing a 3 mm thick vinyl floor covering.

How can I fix the edges together, for example with tape or another method?

With tongue and groove joints and glue?
"Normally," you would apply a leveling compound to the floor or skim-coat the floor before laying the vinyl flooring. I’m not sure if the idea of using MDF boards here is a good one?

WildThing schrieb:
With tongue-and-groove joint and glue?
Normally, you would apply a leveling compound to the floor or skim coat it before laying vinyl flooring. I'm not sure if using MDF boards is a good idea here.

An engineered wood floor does not work because the planks have some flex, which could cause the vinyl to crack underneath.
3 mm (1/8 inch) sheets have no tongue-and-groove joint, and thicker ones are not an option.

The panels cannot be joined at the edges at all because the gluing surface is far too small. It might be possible to screw the panels onto the floorboards?

kesart schrieb:
Using leveling compound is not possible because the floorboards have some give

I thought I once read about a type of flexible leveling compound for floorboards. With MDF boards, I would always expect the edges to break off.