I hope you didn't mean to call the Ramban, the SA, and the Rashba an Apikores, chas vashulum.
We're talking about being melagleg nowadays.
It's not like it's not a settled issue. Exactly how many gedolim can you find today that are against it? And yes, most rishonim and acharonim were for it. If you are against it, don't do it. Don't act like Satmar with the eiruv.
The opponents are your usual culprits. None with an abundance of yiras shamayim dictating their opposition.