Some sows will squash no matter what the situation, others wont. Most squishing tends to happen in the first 48/72 hours, after that they should be on their feet enough to know to get out the way
I'd say the house isn't big enough, even if you're not going to put rails up, I'd make sure that they had a creep area available to get out of mums way, especially when she's about to lie down/get up. Can you extend it a little bit? Remember the weaners will also need to somewhere to sleep and they can be a reasonable size by 8 weeks - and if she has a lot it'll be a tight squeeze!
Also you need to consider what you're going to do if for whatever reason you need to get into the house with her/weaners. I'd recommend a creep area of at least a metre squared, and then a good chunk for mum to get comfy in.