Slapping on a 5-string

Well I have a slight problem.
I'm trying to slap with my hand aimed downward (ala flea) and I have an issue with my 5th string.
The song I'm practicing is Higher Ground (RHCP version), so there's a lot of E thumbing.
The problem is, that my 5th string keeps ringing out. (by 5th I mean the extra H string)
I assume that the part where my thumb comes together with my palm (that lump) keeps gliding over it and thus making it ring too much. I've tried to position my palm so that It's actualy muting the H string, but then the fleshy part on the other side of my hand (on the side of the pinky going down towards the wrist) that sticks out, keeps muting the E string when it's not soposed to.
Right now I just keep turning and adjusting my palm in various ways to try and find the perfect position that is also comfertable.

I am aware that slapping on a 5-string is much harder, plus I have an Ibanez GSR205 and if I'm not mistaking it has a small neck and even smaller string spacing compared to regular 5-strings.

So, does anyone have any suggestions on palm position? How do you avoid the 5th string ringing out? Is it just practice and nothing more?

No matter what the answers I would still like to know how you position your hand, because I believe that really is my problem. A picture, diagram or video if possible. Thank you

Also I keep hitting the A with the very tip of my thumb even when my thumb is at a near horizontal angle, but that's a smaller problem because I can mute the string with my left hand if needed. The problem is fitting my thumb in the cramped space.

Try muting the lower strings with your thumb on your fretting hand or your fingers if they aren't too busy

I don't do a whole lot of slappin'
But when I do, my thumb is more horizontal so it doesn't hit any other strings.

I tried muting it with my fretting thumb, but that only results in less mobility on my fretting hand. Also my fingers are busy muting A, D and G, and now I'm certain that's what they're soposed to be doing.
I keep my thumb at an angle, It's not exactly horizontal (because then my slap sound suffers) but it it's rather close to it, so I assume that's ok then?

I've watched dman's slap videos 1 & 2 (and some other 5-sleppers on youtube) and I'm 100% sure that the trick to domesticating the H is in the slapping hand. Although, I've never seen the dman slap a 5 string without using the H, I've seen others do it a lot.

My problem lies in the lower part of my palm, that meaty area before the wrist. That's what I need help positioning.

You're from Germany or around there. For the others in this thread: H == B.

I'm still not sure whether or not I'm gonna go with this guys way of slapping but it seems to be more or less the way Victor Wooten does it going by his instructional video, other than that... do it slowly. Practice makes perfect mate.

good luck

i have a five string as well
the way i avoid hitting other strings is by tilting the thumb further and further up if i slap the higher strings
also i use the fleshy part near my pinky finger to mute the strings below the ones im slapping
and that seems to work fine for me
i did take some pics but the forum wont let me upload them so this will have to do

Hey, thanks, that's the kind of tip I was looking for
I use to try slapping like that guy showed in the video, but it's not the best position for me.

Plus, I've re-watched dman's slap precision video while carefully looking at the critical bits.

I have no more problems with A, D and G ringing out (well I do sometimes, but that's just lack of practice now).

The H or B string (I'm from Serbia, I forgot it was different) is still a minor problem. While I slap the A string I can mute everything else and it sounds fine, but when I slap the E that top string keeps ringing out.
Right now, I believe the reason why I'm having problems with it is the thickness of the string, which leads me to believe it's just a matter of practice and rehabilitating my thumb motion.

One thing I'm curious about the most. What do you do with the lower fleshy part of your palm (when slapping downward like dman)? Do you rest it on the string above to mute or do you keep it in the air and away from the strings? To me it seems like I lose a lot of power and get tired way too quickly when I keep it away, but it's not close enough to mute the string I'm slapping by accident...
I know these are all minor details and that most of them are subjective, but I'm trying to avoid making the mistake of learning a poor technique or developing bad habits.