So, it was previously (a few years ago) discussed on the Discord about the engineering difficulties of an aerospace cruiser. And having re-read some of the source material, I think you can avoid some of those difficulties with requiring significant engine burns to remain in a forced orbit - you’re in an atmosphere, so couldn’t you use nuclear thermal rockets or the tractor-pressor beam and the atmosphere as reaction mass? You’re still going to be using fuel, but that’s less troublesome than having to cart around your remass as well, no?
Or are aerospace cruisers too heavy for that to work? I think you could run into some difficulties with insufficient mass flow rate for the thrust you’re trying to get and the thermal or other engineering limits of your equipment.