Staying on plane tips/drills?

In my quest to get down in to the 70s this year, I hit a snag around 86-88 about a month ago. Suddenly 90 was out of reach, so I knew my game needed some work. Changed my grip and address, we're back under 90. Grip was wayyyyy too strong. Switched to some 30 year old Ben Hogan Director blades -- shorter distance (I was already a short player, I have a short backswing) but I'm making better contact. Short game is still good, putts 26-28 a round, on the course with good greens.

I'm a fat guy with a wiiiiide belly and tend to come low and inside on my backswing, end up blading a lot of iron shots off to the right and driver is just not an option for me -- snap hooks all the way. Gotten pretty good at 2-irons off the tee.

I can hit a blade 2-bar but I can't hit a wood to save my life. I can't stay on plane! I'm too far inside and I know it. Should I try to buy one of those huge things with a hole in it to swing along? Any drills I can do? I'm very frustrated with my game -- I'm playing 4-5 times a week and on the range the other one or two with a day off per week and just not getting better anymore, the good shots are a lot better but the bad ones are still just as numerous as before. I fear I'm practicing bad habits.