Tip: When determining a time limit, remember that players won't be as familiar with the level as you are. If you normally complete the level with around 100s left on the timer, others might run out of time on their first try.
By the way, it would be nice if the customisations were all put in a single extra byte or at least, two bytes since currently, you're using three binary settings in three bytes (extra bit, which I count here as a whole byte + two extra bytes).
This is definitely an extending bridge that hurts you. For real, it's a nice twist on the existing sprite and the options all appear to work as intended. The only bug worth noting is an issue with the original extending bridge sprite, where if you do a crouch jump into it (and in the case of the hurting bridge, you have to damage boost), you get warped to the end of the bridge instantly. Some may find this useful, others may not, but since it's a problem with the original sprite it's still being accepted.