I'd probably take all your 40-50 CM pins. Maybe bring 1 or 2 LE's in case you run into another collector, but honestly if you run into another collector if you just give them your info you'll probably have a better chance of making a good trade that way.
That being said, here is the complicated way that I organize my traders while I'm in the parks:
(Note: This my style of park trading. It might not work for you specifically, but I figure I'll give a shot in explaining it anyway. Granted, I have never stayed at WDW for more than five days, but this is how I stay organized when I bring about 30-50 traders.)
If you have 40 traders do the following:
1. Put pins into groups of 10 based on their value. Put each group into a zip-lock bag.
2. Label the bags 1-4, with 1 being the "these pins aren't worth anything to me" pins, and 5 being "I might want to hang onto these" pins.
3. Bring bags 1 and 2 with you into the park. Maybe keep one in your pocket and one in your bag. (So you have about 20 pins on you at all times.) These will be your traders.
4. When trading, keep a third ziplock bag for the pins you've traded for.
5. If you have time, that night go through the pins you've traded for and deem if they are: A) Definite keepers, or B) I may trade these again.
(If you can't do this every night, try to do it as often as you can.)
6A. If they are keepers, put them into a special bag/box named "keepers".
6B. If they are trade agains, put them into bag 1-4 depending on their value.
7. Once you run out of pins in bags 1&2, if you have the time go through bags 3 and 4 for more traders. If you don't have the time, just grab bags 3 and 4 to take with you, and just be conscious of what pins you're taking out.
Or, if they're all just "yeah I don't care about these pins" pins, then just grab whatever bags you want and keep your trades separate! Then, once you go through all the pins you brought, go over the ones you've traded for and organize those as stated in steps 5 and 6. Keep going until you run out of pins!
Sorry if that was complicated or if that was unwanted advice. ;-; The real important thing to remember is have fun. And I hope you have a wonderful vacation!