I see on one of your pics the seal came with a sleeve, sometimes you can use those. Again I am not familiar with your application, but your bolt and socket idea could work. I've fabricated seal tools from pipes and caps before. Regarding the seal placement, if there is no seal stop as Tom mentioned, you should have some leeway. It wouldn't take much to have the lip not riding on the old path. Regarding the seal being perpendicular, if you are using the seal tool, it will drive it in straight. But if you were to hammer it in, then you have a potential to not drive it in straight.