Your idea may be workable, but something large enough to manage SSTO (a matter of tank sizes and volumes) is going to be dang difficult to land with a parachute.

Believe me when I tell you that there are few SSTO ideas that I and the people I have worked with have not ground down fine years ago. The last original design concept I've seen was McKinney's Roton, and that didn't pan out very well.

Propulsion technology has not advanced all that much since Apollo, although there are engines like the SSME operating at much higher pressures now that can squeeze a bit more Isp out of the standard fuels.

The idea of aerospikes on SSTOs is decades older than Venturestar, and we weren't stupid enough to put it on a lifting body. I've worked on designs for horizontal landers, vertical landers, combinations of both, variations on expendables, partial expendables, aerial refueling systems, air breathers, nuclear systems, and pulse propulsion. Hell, the first company I started with worked on pulse propulsion systems (hell, I'd write a book except my memory of events and times blurs together, and I can't convince Gary to do it.)

And you know what? Almost all of them could be made to work.* All that is needed is for someone to buckle down and do the hard work required without having to worry about keeping fifty thousand people employed, dozens of NASA facilities humming, and a hundred senators happy about people building parts in their districts.

The big aerospace companies aren't going to do it. I first found this out back when I sat across a table from John Yardley at McDonnell Douglas, trying to sell the Phoenix concept. They just can't think that way, unless the government or industry pays them to. The idea of something like even the Skunk Works building a spaceship on spec and private capital, and waiting for the market to show up, is inconceivable to them.

The personal computer business had to start in a garage. A corporation like IBM couldn't do it. Unfortunately, the analogy fails here. You can't whomp up an orbital spaceship in a garage, although some people have given it a damn good shot. I'm not sure where to go from here. Maybe the suborbital market can bootstrap itself into something real. I don't know.

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* As Kipling says, "There are nine and sixty ways of constructing tribal lays, And every single one of them is right!"