Chris J,
I'm on daily 5 mg Cialis too and have found that just very occasionally I can have a reasonable erection even without using the pump. Whether it's the build up of the drug in my system or not ( after 3 months) I'm not sure but none the less it's pleasing. Or the HT treatment isn't doing its job properly but as I still suffer from flushes I'm sure it is. I was advised that using Muse alongside Cialis could be a further option to consider but I haven't gone down that route yet.
What fun having PCa is - who'd ever have thought we would be having discussions like this!
Good luck with whatever you decide to do.
John