Spawning And Budget Glitch Issues

Okay, I'm working on my first map. It's kind of like one of those infection journey ones.

I have some spawn points for the humans under some Barriers which are on never respawn, so that when they break the barriers they are able to spawn at those spawn points acting as a sort of checkpoint if they die in the next part of the map. But when I did this I had some issues where they could either spawn back at the beginning or where the barriers were. So I tried to block off the spawn areas with some crates put on a timed don't appear at the start respawn, but then the timing was always wrong, it really varies how long it takes to get to the barriers and break them. So I added an Instance Switch but the area where the spawns are is kind of big so the switch doesn't fully block off the spawn area most of the time. So I need help with this.

I was wondering say I had 4 starting points and 4 respawn points for humans, could I still have a full team of maybe 12 humans? Because then I could make the spawning area very small so the switch could block it off easier.

Also, I'm running low on budget, so I took a look at the Ultimate Budget Glitch thread on forging 101. At the end it said I could budget glitch a map partway through, like mine. I didn't really understand how to do it though, so help with that would be appreciated too.