"i modified the oldschool to instead, be a transition to guard. A SUPER tight, equally unstoppable guard pull. After some thought, i figured maybe i could come up with something for bottom-side that was similar. "
The game changes a bit when you go from the bottom of the side mount to the half guard. So I don't think you can come up with something for the bottom of the side mount that's similar. And even if you could, with some experimentation and imagination, it would never be very high percentage because your opponent, who is tight to you, has all the leverage and you don't.
"The problem is, the looseness on bottom seems to invite knee on stomach, or mount"
Not if you do your escapes correctly. If you just kind of "ball up", i.e. put your near knee close to your chest or in some cases your near elbow, it will be very hard to mount you or put a knee on your stomach.
"Do you think its possible to get a tight head and arm control, and create the space between our hips and have that be just as effective? "
Don't think so. See above.
"After three years of playing a sakuraba-style loose submission attack from the bottom (and loosing too many matches) the tightness i've developed recently is really helping. "
I think the reason this seems to be working for you is that this sudden change of your style is confusing your opponents a bit. Give it a while and it might very well be WORSE for you.
Another reason: Constantly trying to submit the top guy from the bottom will cause you to get submitted often - unless you're very good at it, like Sakuraba. Submissions from the bottom of the side mount and the bottom of the back mount and even the bottom of the half guard sometimes can be risky if you aren't comfortable with the fundamentals of these positions. To attack a limb, you have to extend your arms. That makes your OWN arms and also your neck a target for the top man - who's got more leverage than you. Kimuras and heel hooks, for example, can be a threat from bottom positions, but in my opinion, those types of escapes can be overdone.
I'm sure that Sakuraba knows the standard escapes very well too. I've seen Sak do some slick guard passes and other moves that are standard BJJ basic moves. The things he does sometimes look cool, but you can believe that he's got the basics nailed down very well, as well as his bag of tricks.
"Also, my head and arm control ..."
I would personally forget about grabbing his head and arm from the bottom, or just grabbing him in any way from the bottom :) You can experiment with this of course, along with doing the known high percentage escapes that come from creating SPACE, but I wouldn't count on it. But who knows, experimentation is good, in general, and maybe you'll come up with a trick or two that can really help you at times. But without the basics, you will always be stopped dead in the tracks by a good grappler.
"Tell me what you think about this (let's assuming he is on my right side): Getting my left arm under his left arm. What i mean here is that both of my arms are at his side between his left arm and leg. "
This sounds very similar to what me and some other guys on this thread have been advocating. It's a part of Michael Jen's "pin prevention system", which revolves around the principle of not giving your opponent full chest to chest control and not giving him the chance to wrap his arms around your body and pull the two of you together. Matt Thornton's "boxing hands posture" is kind of similar.
If he's on your right side, your right elbow (note - in these cases, when I say elbows, I mean the bottom half of your forearm, close to your elbow.) is pushing his left hip and your left elbow is pushing his left armpit. Whenever he tries to wrap his left arm around your head, push his left elbow off your head with your right hand, while simultaneously raising your head to duck it under his arm. Then put your right elbow back on his hip.
What you are doing here is "killing" his left arm so he can't use it to wrap it around your head (cross-face) or pull up on your right arm. And these two things are his most powerful weapons he has to keep you flat on your back. You just took that away from him! Good for you, bad for him.
From this position, shrimp and/or bridge several times to get onto your right side. Then just push on his hips, stomach or legs with your elbows or stiff arms and either pull guard or get to your knees. If he's in some form of scarf hold (basically lying on you on his side), it can help to push with your top elbow between any two of his ribs :)
Actually, I PREFER to just be completely on my right side, pushing with my elbows or straight arms (usually I push with straight arms; straight arms aren't that dangerous for you once you're on your side), than to be flat on my back with the "pin prevention system". This is because I'm closer to an escape that way. But sometimes you get flattened out a bit and then it can be very handy to put your left elbow under his left armpit like that.
Another good arm position for you is to underhook his RIGHT arm with your left arm and get his weight over your head with shrimps and/or bridges.