6/8D Bet spread-pen?

I have a few questions for the pros

I have realised that 6/8D can be beaten (I typically play 1D or 2D-Vegas downtown or Reno), and have started playing as follows with success-following Don S etc. Bet min $5 or $10 (depending on availability of tables) from the begining of a shoe. If the TC drops to -1 leave (or pass a few hands until it becomes +ve-telling the ploppies that it may improve the card flow etc). Start ramping up at TC+2 to $25 to $75 at TC+4 (avoiding black action call). What type of pen is needed to get an adv using this? is 70% (or better) sufficient?

I would like to simply play only +ve shoes (spreading $25-$75) -that means playing only a very few hands or none/shoe, but this is extremley difficult because of ploppies getting mad-PB geeting suspicious, not many spots/tables free etc. If I can play this way (only +ve) do I need a minimum pen to get an adv? or even say 60% enough to get an edge. (I know that in general the deeper the pen-better the edge and also high TC's gnerally come towards the end of a deep shoe).

Thank you for any/all responses

The problem is that you will only see TC+4 a couple of hands per trip and you need to spread if you are going to beat the shoe. I like to jump my bet higher at TC+2. In the case you describe of $5 min. I'd bet the min until TC+2, then jump to $60 or $80 and stay there until the count came back down, I like to bet red on top of green, seems to draw less attention. But I also try not to stay too long in one place. Any pit will, after a couple of shoes, know that you are counting, but most won't care and won't take action unless they have nothing else to do or you start winning too much.

I have realised that 6/8D can be beaten (I typically play 1D or 2D-Vegas downtown or Reno), and have started playing as follows with success-following Don S etc

Be aware that mathematically the gulf between pitch and multiple deck is huge. Combined risk/ev measures at SD can be thirty to forty times as high as an equivalent multiple deck game. Of course, noticeable compensations exist in terms of cover.

What type of pen is needed to get an adv using this? is 70% (or better) sufficient?

70% should be sufficent.

I would like to simply play only +ve shoes (spreading $25-$75) -that means playing only a very few hands or none/shoe, but this is extremley difficult because of ploppies getting mad-PB geeting suspicious, not many spots/tables free etc.

A good approach, but as you say it can be impractical.

If I can play this way (only +ve) do I need a minimum pen to get an adv? or even say 60% enough to get an edge.

A difference exists between getting an edge and getting a worthwhile edge. 60% pen will not get you a worthwhile edge.