I currently ride into work once a week and am in desperate need of some input.

I need to bring my 2 sandwiches, an apple, a banana, a few granola bars, a small computer repair kit, a 'paper planner', bike repair kit, a towel, a pair of pants, a shirt, underwear and socks, a pair of shoes.

It's pretty hard to store my stuff here at work so I need to bring this all in one ride.

Any ideas on how to stuff this onto a road bike without luggage rack, without stuffing everything into a backpack (not too great of an idea for a 50km ride)?

The reason I ride into work only once a week, is that the distance is currently too much for me to ride in more often. The ride is 50km one way. I tried riding into work by car with the bike in the trunk and leave the car at work and ride home by bike. This however doesn't work most of the time as my sister in law lives in the city I work in, and is moving, so I need to do some moving for her as she's currently in a wheel chair.
The amount of days I ride to work by bike, and the fact that I have some trouble not being able to ride as often as I would like to are not up for any further discussion though. It's all about how to get my stuff to work by bike.