Chassis/ front outrigger - how much rust to cut back?

Hi,
I'm currently making a start of repairing the LHS chassis rail where the front outrigger / front cross member joins. Just after some thoughts on how much rot needs cut back on this, on my van.

I'll be starting on the smaller area by the cross member so wondered how much this needs taken back? I've made the 10p sized hole at the bottom (where it has rusted out). There's a bit of pitting around the area, and further out what I would call surface rust
Blue is where front cross member was attached

Thanks

 

After that's fixed, I'll be onto the outrigger side which is a bit more rusted.
Again how much to cut out? I was going to replace a little into the upward angle area at the front, and then a few inches back from the end of the outrigger at the rear?

 

In general terms, nibble away at it until you're satisfied you got to the good stuff.

 

Hit it with a hammer. The replacement steel is 2mm thick. If theres a hole then its likely theres a lot more thin stuff around it.
In the end, it can be less faff to design cuts and welds into solid metal that suit the reach of your cutting and welding tools, (angle grinders cant reach everywhere, reciprocating saws aka sawzall like slicing completely through but cant hit the corners) ... and start with a complete replacement section that you cut down (into several pieces) to get e.g. the formed bends in 2mm steel in the right places.

Rather than fill in many 10p sized holes that may burn through around the hole when you wind up the welder enough to penetrate 2mm metal.

Go for straight line cuts into solid metal.

 

Thanks for the replies
I should have said, 10p sized cut out was only made to get a reciprocating saw in removing the bits that were pure dust, before then cutting out a larger straight edged section.

So I had thought for the inner chassis side maybe a 4 inch rectangular section slightly wider than the cross member welding points.
For the outer chassis rail, thinking maybe a 8inch C shaped section of schofields repair panel for this area. From where the rail starts angling up for the front beam, going back about 8 inches?

I know it's quite hard to see in the photos, but do you think that gets me back to good enough metal with only minimal surface rust?

 

I got the VW preservation ones and they were good quality .

 

As the chassis rot from the outrigger is mostly going to be outside in where water ran into the jacking point, going a short distance either side will probably do.. but dont be surprised if it needs more..

Using a ball peen hammer you should be able to hit 2mm thick chassis metal quite hard.. if it dents its has become thinned with rust where it hasnt come through yet..

Schofields is usually the go to place for these panels..