The issue with diving a wetsuit and a steel tank is that if you were to have a catastrophic wing failure at depth at the start of your dive, you might be massively over weighted and unable to get to the surface.
If you can go down deep enough to have significant suit compression (say 100 feet), with a full tank, and still swim your rig up with no aid from your wing, you should have no problem diving with a steel tank and a wetsuit. When I first got my HP130, I took it out and dropped to 90+ feet, had my buddy make sure I had no air left in my wing, and tried to swim it, plus some extra weight, up. I had no issues swimming it up to 50 feet (where my suit was significantly less compressed and swimming it up was no longer difficult at all), and thus diving with a steel tank and my wetsuit is fine for me.
If you find that you cannot swim your entire rig up, but you could if you had X pounds less, you can use that much as ditchable weight, and then you should still be fine diving in the steel. But beware that by ditching weight, you will be inherently very positive when you are shallow and your suit is no longer compressed....you may run into issues of not being able to maintain a safety stop, so your best bet would be to dive dry, that way you have the redundant buoyancy compensation.