Those two issues, getting stuck and engies being screwed, were some of the trickiest to solve. I'm pretty sure I've put them behind me though; despite just recently showing the map, I've already re-iterated on the layout many times. In any case though, I'm not considering dividing the map into rounds because it would defeat the purpose of the looping track.
People can't get stuck when the spawns switch. let's say blue captures point 2 (refer to the overhead screenshot): when that happens, the indoor half of the map opens up, and the spawns switch sides, so that blue is spawning near point 2, and red spawns near point 4. However, a wall pops up behind red's spawn to keep them from flanking blue. Anybody that's hanging around the outdoor area can still run along the track to where the cart currently is.
Basically, nomatter where the cart is, you can run wherever you want, except through the wall behind red's spawn. Of course, a red or blue player might run out of spawn right before the spawns switch, but that could also happen to red in the third section of goldrush, and it wasn't a big deal there. Plus, if your smart you can wait in spawn a few seconds until the point is captured, and then just run out the other side when it unlocks. Since each team has one spawn zone with locking/unlocking doors, you don't get isolated on the wrong side of the map by waiting.
As for engies, it's just going to be a difficult map for them. It shouldn't be unfair, though. I've given red some easy spots to build up near their spawn, and if they're quick they can build up closer to blue. I don't want engies to be as effective as they are in goldrush anyways, but they should still have a fighting chance.
For blue, engies aren't any worse off than they are in goldrush. They just need to delete buildings when the next half of the map opens up.