Yes—using a normal backpack can work fine for a hike. Camera gear is usually tougher than many people expect, so the main goals are preventing hard knocks, protecting glass surfaces, and keeping moisture out.

Practical approach:

• Wrap or place the camera body and each lens in separate soft pouches, or use spare clothing as padding.
• Pack gear away from hard-edged items and spread the weight around the bag rather than stacking everything in one heavy lump.
• Use the waterproof protection you already trust for clothing or other gear to keep the camera dry.
• Think about access: if the camera is buried too deeply, you may not use it. If you expect to shoot often, consider securing the camera on your backpack straps or chest area with a suitable strap system.
• Travel light. For hiking, bring only the gear you really expect to use.

So, a DIY solution is less about building a rigid insert and more about using soft pouches/clothes for padding, careful packing, waterproofing, and a carry method that balances protection with accessibility.