Gas venting can be an issue in suppressed guns hence PRI charging handles, vented buttons replacing forward assist buttons. 

I want my FA. I will do the CH mod. But what if we simply vented the upper via the underside of the forward assist tube? My idea is drill 3-5 small weep holes along the 5 o'clock position starting right up next to the reciever moving outward toward the actual forward assist button but not to the raised lip the button bottoms onto. 2 slightly larger or 3 to-5 small vent holes might do it. Positioned at 5 o'clock they direct vented gas downward and away from the shooter AND still allows functionality of the FA.?

Or drilling several holes thru the sides of the reciever at a forward facing 45 degree angle above the E port cover, matching on the other side, directing gasses away from the shooter. Measure and drill with the CH in place so the holes pierce the CH in its track.

 that's an interesting idea. That's an interesting idea. How hot does the gas get?   would your trigger hand be at risk of being burned?

Conceptually, I think your second idea above the EP cover would work better.  I'd start with the right side of the receiver and try it that way before doing hte left side (assuming you're right handed).  

With AR parts being as cheap as they ever will be again, now is the time to experiment.  

DO IT.  and then post pics and an AAR.

I've done both the o-ring and CH slot and drill mods on my stuff that gets suppressed. My 9mm has it's FA plugged with no holes drilled anywhere and both grendels still have FA. No gas blowback problems at all and when fired really wet I don't end up with shit on my glasses either. The slot and drill mods really do a good job and I've never broken a CH due to it being weak after the mod.

Got any pics of the drill and CH slot mods?

I don't have any with me, but I'll snap a handful as soon as I get home from work

Thank you. I'd like to see this as well.

Here are some pics I've bookmarked. Adjustable gas blocks have so far helped me not need these mods.

I think you're past the point of diminishing returns on gas to face prevention mods... reduce the gas to the upper, and none of these mods are needed.