Hi compostpope.
That’s interesting about the squash. They do like as much sun as possible to ripen, especially last season! Perhaps there was also some competition between the roots of the squash and those of the raspberries as both send out roots quite far. I noticed this last year – the plants in the bed next to my squash bed were noticeably smaller on the side closest to the squash. I think the roots of the squash were growing into the edge of the adjoining bed.
I’d grow salads in a partly shady spot. They also have less roots and would probably get on better near your raspberries.
Andy