The only saddle I start colts in are my barrel saddles. I can lift it with one hand, it keeps me in the saddle, and it's comfortable.
Honestly you'll just have to get comfortable in a western saddle. The change will be different but you'll survive, I promise. I am not one to really care whether a saddle is a close contact english saddle or my heavy roping saddle. If you have the feel, you'll feel the horse through anything. I'd find an older cheap barrel saddle if I were you. Learn to sit back right in a western saddle. You'll have to learn to do that anyway if you're going to work on a ranch starting colts who may be buckers.
My colt starting saddle:
Honestly I've never seen a synthetic saddle look or fit a horse right. I hate the feel too, there's no decent weight in the stirrups, and nothing you can do to keep seated during even the worst "baby horse moments".
That saddle is a Hereford barrel saddle from the 90s. I will still barrel race in it too, trail ride, move cows, etc. Love it more than my more expensive saddles. Bought it for $400 three years ago.