I can do the top-of-a-col pic too:
That's the heaviest bike I own too. Although on that particular day it was an optional rest day (or do the highest col of the tour, guess which I chose) so we were more lightly loaded as we could leave our clothes back at base. I had two full decent sized panniers, probably about 12kg.
10% pyreneean climbs that go on for 10km+ don't bother me at all. I got up them, though my back was sore from all the grimping at times. The problem is going to be that I want to be able to get round the Fred Whitton which has much steeper gradients. And I won't have as low gearing.
I've done another turbo session tonight. Interestingly in regard to my HR query elsewhere, raising the front end of the bike a bit has helped (despite being on a support, it was too low I think). I also used a fan.