Can the ProTrail be set up as just a bug tent? I don't think so. It's an awesome shelter, but I don't think it meets that criterium. I could be wrong, though. However, the TT Stratospire is a true double-walled tent that can be set up as just a bug tent. And I think the newer TT DW Moments, too.
It really sounds like you want a more conventional double-walled tent, with the option to just pitch the inner (bug net) alone. Lightweight alternatives are rare. Big Sky is the winner in weight, but might break your budget, and their weight gains may be made by using some very tenuous fabrics. Others seem to like the BA Copper Spur line, and the REI Halfdome isn't a *bad* bargain option.
Around here, though, you're going to get more fringe recommendations. For instance, a 2P pyramid tarp with inner net. Something like the MLD DuoMid with their inner net would fit your bill very nicely. But in my opinion using an inner with a pyramid is sort of missing the whole point of a pyramid, and very nearly negates any weight advantages over a conventional tent. But it would fit your criteria. I have a hard time thinking of something faster and easier to set up than a pyramid. (Other that a few Tarptents, like the Moment. And I think the newer DW Moments can indeed be set up as just a bug net. I used to set my Moment up in 60 seconds for the minimal two-stake pitch. They are probably worth checking out.)
In fact, I use the MLD DuoMid as my go-to solo shelter. I use a SuperLight bivy, though, not an inner net. As a side/belly sleeper I have no issues with netting on my face, and the bivy acts like a grounsheet, bug net, snake barrier, and protection from light rainspray or spindrift if I cowboy camp or use an established shelter of some sort. The DuoMid is a very cozy 1P shelter capable of fitting you and all of your gear, that can hold 2 if they don't mind being friendly. A trekking pole can be used as the center pole, either with a polejack or just by sticking a rock under it- but most poles aren't long enough on their own. I've never had a problem finding a rock. :)
In general, I'm a BIG fan of pyramid shelters (I can go into why if you like) and think that if you could have only one shelter it should be a pyramid of some sort. My larger "group" shelter is an MLD SuperMid, and I do have an inner net for that, but I bought the inner when I was still experimenting and I have found that the bivy is the best solution for me.