Hammerite underbody seal + Waxoyl

Hi,

My plan is to steam clean my chassis, and wire brush it all a lot, and then paint on with underbody seal stuff. Apparently, it's supposed to convert any remaining surface rust to a stable form. I'm not sure if primers do that, so I'm thinking it's better to just apply the hammerite/waxoyl directly? Good idea or not? I'd love to get it sandblasted really, but I don't have the resources for that :/

i did
2 coats of red oxide
2 hammerite enamell
1 underseal,

proper job,
the red oxide takes in any rust, the hammerite seals with a hard finish , the underseal is a self sealing waterproofer, if you just use under seal it will soon dry up due to dust etc, will rust thru quickly