Thanks for the info and suggestions guys!
It sounds like the RC Haulers have enough space for my RC gear, but I don't have space for my other stuff in that situation.
I looked at the Motocross bags: They are indeed very nice - I had a look at some brands, I really liked the Ogio and Thor (And Fox had a really nicely square one, but it seems to be discontinued?) - If I want one I'll have to find a dealer in the Netherlands - I'd prefer to see what I'm buying first (this counts for all the bags/cases etc. by the way).
After some further searching I found 2 Samsonite cases that 'could' work - their strength (and Achilles' heel) is the fact that they don't have internal pieces to seperate parts.
And just a minute ago, I found this:
http://www.atlantaluggage.com/media/..._a_black-1.jpg
A luggage cart. I didn't know these existed (not for consumer use/foldable anyway), this could work well for me! I could just stack the luggage instead of looking for a bag or box in which everything fits: One box or bag for the RC, parts and tools, the tent, the sleeping bag, the camping pad and potentially a table and seat). I could just buy some extra bungee cords to properly secure the stuff, and wear a small backpack with me.
@philip: Cool story!
It sounds pretty similar to what I do, with the difference being you have a suitcase whereas I'm still dragging around the sport bag and camping stuff seperately - by the sound of it, it's possible though to get everything to fit in a large suitcase?