On a new property I'd go for 70* or vertical panels.  My current house has a number of shortcomings for RE.

I hear what you say about 'clumpy' and my own measurements (by proxy, from my pilot PV system) suggests that 7 days' storage would be needed to carry through those.

Now a 7-day store in the house, or seasonal thermal store to cover the 33% you said still had to come from oil, is not totally impossible at all.

That actually gives me a sensible target to shoot for!

Rgds