Been a while
 

So I desided to come back to SH4. Its been a year. I've picked up TMO, and RSRD campaign. But one question can I run PE4 with TMO or will that mess up stuff

I ran it with an older ver of TMO,,,I think 162. Overall, not sure if it would change any settings in 1.7. If you're running 1.7 it includes Env 5 already, so don't know why you would, unless you prefer it.

From the readme in TMO

17.) Can i run this super cool enviormental mod with TMO?
An Enviormental mod is now included in TMO, so you should not have to run anything extra. You may prefer one mod over another, i can only recommend that you try TMO by itself before adding mods of your own. A word of caution here with enviormental mods in general: The authors of these mods are doing fantastic work and have made great strides. Unfortuntely these mods are having adverse effects on AI visual sensors (confirmed), and possibly even AI underwater sensors (unconfirmed). These ill effects will also effect your watch crews ability to spot targets, being unable to see things that you can see clearly. The enviormental mod included in TM has been tweaked so this does not happen. So be advised that by running other mods, you run the risk of upsetting how well the AI can visually detect things.

Thanks I knew I should have read the latest readme before posting. Thats what it's there for. Sorry.