Solder joints also leave an area where flexible meets solid and this area is prone to breakage.
I use crimp joints with pre fitted heat shrink and glue, they are VW approved but are not cheap. If I have to use bullets I fill them with grease.
I had a nice setup in my last 90 but can't remember what it was!
I'm planning to go for the rear aerial mount and a big spring type aerial!
The radio itself would help if its small as space is tight!
Any ideas?