Twin LPG tanks to single

I have twin tanks in my Range Roverbut I dont do long journeys and would like to free up space in the loading area.

From what I can see, the top tank gets filled first then it filters down to the bottom tank so is it just a matter of running the tanks dry and re-routing the filler pipe to the bottom tank then remove the top one?

Or is it a specialist job?

Ive just had the car MOTd so not bothered about a certificate.

If they are cross linked (which I would guess they are - 99.999% are) both are filled at the same time and used at the same time....

There is always a tiny amount of gas and pressure even in a 'empty' state....

Best left to the pro's if you ask me!!