+1 for Road Fan's advise on saddle set up and positioning. I'll reinforce not using the tension bolt to adjust the Brooks saddles. You can ruin a Brooks fast with too much tension. Some feel that the nose of a Brooks should be ever so slightly tipped up, I have not found it helpful to me with the Professional or the B17. Level to start as said and ever so slightly down in increments. My experience, though no expert what so ever is that your saddle fore/aft position is off. Possible leg length problem you mentioned, see a fitter or a Podiatrist for an orthotic to place in the shoe.

Best of luck in sorting out the saddle and pain problem. And welcome to 50+ forum and to BF. Some pictures of the tandem would be super too.

Bill