The roof
I have been pushing this to the back of the repairs schedule as I was not sure of the best approach but now I am running out of rust to weld up it been creeping further up the To Do list.
The plan.
The front section sub assembly and screen pillar needs to be repaired first and then the cap put back on. The cap will likely be in three sections made up on the bench then welded into position.
As you will see from this image there is not a lot left at the screen edge to weld too!
I need to get the screen out so I can remake the flange properly.
That is not as easy as it sounds as it is bonded in so rather than try and saw my way round it I will get our windscreen chap to remove it and then I will bond it back when I have finished the reps.
That is of course providing it doesn't get damaged on the way out and that is not unlikely.
https://goo.gl/photos/7Dtarg7uaBzWsuSj9
The rusty bits.
The image here shows what I had thought initially was a patch to the roof but it was nail gun marks I could see inside from a rather rough repair. Once all the paint had been removed it was obvious.
https://goo.gl/photos/eTphbSpNiG1rgEey5
In these images you can see small pin holes of rust a various points along the length of the roof skin adjacent to the gutter rail. I could see the sealant had broken down in these areas allowing water to enter I can also see evidence of an awnings fixing marks. So I suspect that this has been a contributing factor in the failure of the sealant especially now I know how heavy they are!
Easy stitch in time is to drench your Bongo gutters in thinned waxoyl and let it find any breaches then reseal with PU sealant
https://goo.gl/photos/S4iwH76VAahPB8Ns7
In this image you can see the areas of rust marked in blue I dont know if they quite match Geoffs rust but they look close and they fall in front of the inner support beams where the three panels meet.
https://goo.gl/photos/aq3NQiLbFmVZA96g6
This image is of the rear D pillar top and shows the rust holes found under the paint and covered with filler, I dug this out having seen Geoffs images. You can see a thin bronze line , this is where the quarter panel meets the roof skin or vice versa and below this is a joddled panel that will collect condensation, that combined with the brazing would promote corrosion here.
https://goo.gl/photos/vBxDe3oMqNiLUL686
So the front section I have described but the rest is a bit different.
I had considered various methods of repair from sectioning it like Geoffs to making up a fiberglass cap but instead , now I can see the extent of the rust, I have decided to unpick the flange from the gutter and slice below the upper roof swage line so as to leave a slight flange, using structural adhesive, insert a repair panel along its length bonding it to the old swage. Once this has cured I will spot weld the flange back to the gutter.
This means I will avoid the inevitable distortion from the weld but there will be no lower swage.
I don`t think it will make much difference looks wise as there will be an awning there and short houses wont see up there anyway.
Doing it like this will allow good access to the remaining roof panel to treat the rust and I may be able to get a body spoon up behind the old repair and tidy that up a bit too.
As to the holes at the back I will open them up with a die grinder and slip up a bit up from behind, as you do,
and lead over the top.
Sorted.
Well that`s the plan
On the Webasto front, I have found a lovely little spot to tuck that away in and I have solved the rear heater problem with a passenger heater unit from a TX1 cab, the box with
transfer box 
is at the repairers, engine is mounted on the stand just waiting for my partner to get it stripped down, my cold has gone and the gratuities are arriving from the suppliers.
All is right with the world.
