rust prevention underseal/waxoyl etc

[bristolracer]

Hi all

My toyota regius camper van is a Jap import.
I assume it has never had any kind of underseal/proofing etc as i believe they dont use salt on the roads in Japan.

As the van represents quite an investment i dont wish for it to go the same way bongos do rotting through everywhere.

So what is the current thinking on rust proofing? Ive read waxoyl is a bit rubbish? whats best bearing in mind it will be me applying it?

Ta in advance