Here's the thing, and why I'm asking. For whatever reason, those One.x numbered skates, including the top tier NXG, have a narrowing where the toe box meets the quarter. For me, that manifests itself as tightness slightly behind where the pinky toe meets my foot, or what you're describing as the forefoot. That would seem to align with what you're describing. The slight difference in sizing between the 7 MX3 and 6.5 One.8 may be the cause for the issues, as could the difference in materials of the quarter. But in the newer model since the 1S, the toe box has a different shape and that narrowing is gone. So you may want to try a skate in the newer lines that would be the Sxx0 numbering system.
Another thing to consider would be a EE width Vapor series if you can fit in the lower volume. That is a tapered boot and will just increase in width from ankle to toe rather than the Supreme which is straighter. It may give you a better fit in that area, and would be more narrow than a EE Supreme skate, so you wouldn't get the loseness up front.
I get that you don't want to go into a shop and get hassled. I don't either. I'm in your same boat because I need new skates and would rather spend the money getting a used pair of the top tier skates cheaper than a mid tier skate at full price. So to go into a store to get fit and try things on with no intention of buying seems a little douchey. Nonetheless, I did just that this weekend and without doing it, I would have bought the completely wrong size of skate. Apparently Supreme sizing changed with the 1S line and I no longer fit in the 8 that I used to. If I hadn't gone in and put an 8 on, I wouldn't have known until I bought one and got it which would have just complicated things. I went in and told the guys the situation. I was up front about what I was going to do and didn't take any more of their time or effort than necessary. All I asked was for them to get me the skate and leave it, I didn't need any help after that. And they didn't pressure me to buy anything or hover over me because they knew the deal. Yeah it sucks for the store, but they weren't busy and get paid by the hour anyway, so what difference does it make to them? I just got off a chat with a Bauer fit rep, and he suggested that anyone do the exact same thing.