What is your actual current goal: To build strength? To increase muscular size? To compete in skateboarding events?
Is the skateboarding recreational (for fun or your only transportation) or are you competitive? If you're competitive, then it's a matter of training like an athlete and treating the skateboarding like any other sports practice and working . If it's recreational, then it might be best to deal with skating at less-than-100% for the short term while focusing on improving gym performance.
Figuring out exactly what you want to do will let you figure out a better plan to get there. But without knowing any details, yes, you can be fine only squatting/hitting legs once a week with a well-designed program.
Also, like Shralpinist said, workout nutrition like Plazma or Surge Workout Fuel can definitely cut down on soreness and help with recovery.