I ended up with the ST60 wind/depth/speed even with the same situation. We decided to just use the GPS dislay not integrated with the wind/water instruments for our VMG. Pain because the GPS is on a swing arm into the companion way rather than in the instrument cluster. Really thought hard about the TacTic stuff but decided the cost was better spent on the sail fund. Rather than bulkhead mount, we ended up fabbing an integrated instrument bridge across the weatherhood like the J105s, and then had to provide wire routing. TacTic gear would have solved that problem. I struggled with what you are facing and could not solve it without the extra couple hundred bucks for the integrated ST60 package. Puts you near the costs of TacTic. We were almost to tying in the autohelm, but that extra step should have pushed us to newer Raymarine or the TacTic set.

If interested I have some pics of the instrument bridge, the wire route covers and internal moulding/wire raceways to get all our wires off the bulkhead inner face. We are down to Port and Starboard compasses on the blukhead and no wires catch things up on. Drop me a note at jageck@earthlink.net if you want to see what we did.