"Ok, just to change the spider guard position slightly. Now lets assume we are in the spider guard position where you have your left foot on your opponents right bicep. Your right shin is on your opponent's right shin and you are hooking his left leg with your right arm.
Now that there is no hip control, it is difficult to stretch your opponent out. If your opponent puts lots of forward pressure on, I normally switch to an x-guard or even half guard. Is there any way of maintaining spider from here?"
First, this isn't really spider. You are describing the middle of a classic sweep from spider guard, but it isn't a position that you "play" for a length of time.
Second, if the guy is still giving you forward pressure at this point, he should be easy to sweep. I don't know why your other leg would be placed against the shin. Normally you would use the free leg as either a lifting hook or use the knee to "boost" his near leg up as you send him over. You can in fact take his back if you do that, spinning your head under as you throw his leg over your body.
That said, just going to x-guard is a very viable move here, and is a common spider guard strategy.
sure jonpall...
Say that you're starting with both feet on the biceps in normal fashion and you have your sleeve grips...Now take your left foot off his bicep bring it below his arm and continue to circle it clockwise around his right arm, but now as you're bringing your foot downward to his bicep, have your foot so that the arch is in the crook of his elbow and your toes are pointing down. You need to really get onto your right side with your hip off the mat almost like your going to roll over your right shoulder and be at an angle to him. This position is the cross roads of 2 great offbalancing moves that go in opposite directions...1 is to bring remove your right foot shove that upside down left foot under his arm and continue to roll over your shoulder for the oma plata. The other direction is to take the upside down left foot off his bicep rotating it in a large counterclockwise circle ending near where you'd put it for a dlr hook, using it as a pendulum to force him backwards and to his right. The other foot on the bicep pushes his elbow high in the air and helps to push his left shoulder backwards to mounted position...Some failed sweeps/subs leave you in vulnerable positions. The worst thing that happens here is that you arm positioned to begin dlr guard or you can continue with more attacks like an armdrag since you're already at an angle to him and he's probably leaning forward to avoid the backwards sweep.
Of course there are a ton of other things to do here, but this is a sequence example that really demonstrates the movement and flowing that this position allows.