I think the lack of toilets on the pop side needs addressing first.
I suspect the problem with toilets in the vicinity of the main stand is that the space is pretty much used to its maximum already. Where would they go? In the 2000's and early 2010's you'd have been able to nip underneath the main stand and into the then-Noel White Suite to use the toilet there, or the ones adjacent to the club shop, as gross as they were! We've lost both options now and as others have pointed out, they've been replaced with the toilets on the far side of the Community Sports Hall, which I appreciate would be a big ask for those with mobility issues.
The only long-term fix I can see is a total reworking of that entire side of the ground into a single, pitch-length main stand with all facilities (corporate, media, amenities, restrooms, club shop and office space) considered and included. Highly expensive and at odds with the Sports Hall development but entirely necessary in the next 15-20-30 years I think.
Edit, to add: I think what FC United have at Broadhurst Park is what we should be aiming for.