I'm a 3.0 male and just last night played a doubles session with a 5.0 female, a 4.5 male, and a likely a low 3.5 male. I play these sorts of mismatches often. Here are my views for what its worth. Also I would be happy for any feedback from more experienced players that might disagree or add to what I have to say.
1) I don't try to poach as aggressively when I am at the net. I do let more balls go by and try to "cover the lane" a bit more this allows (and forces them to let) my partner to play out more of the points. As long as the ball is going over the middle the better player will usually have a shot at it.
2) However I try not to play safe in my returns and ground strokes. If I play safe and hit easier/softer/ higher over the net, groundstrokes or returns then the opposing net player will just put them away, or the other person hitting ground strokes will move in and put me on the defensive quickly. I try to keep swinging and hitting the ball aggressively. I may make more unforced errors but that is expected. If some go your way it may give the opposing side pause about how weak you are. And a UE that is hit aggressively is not as disheartening for us (and confidence building for the other side) as popping something up for the opposing net person to smash at your partner. 4.0 and better players are often at that level because they are good at putting away the put aways. If you know you will be the weaker partner then when you practice practice hitting the ball hard.
3)Sort of the exception to 2 is when I am at the net and have a medium difficulty shot. I don't try to do too much with it and try not to hit it out or in the net. If I have a good chance of ending the point or at least forcing them to hit a defensive ball on the run or at their feet I think that is good enough. We keep the advantage instead of me hitting it out or in the net. But if it is an easy overheard at the net or something like that then sure I go for it.
4) If I am rallying cross court with a clearly better player after serve or receive, chances are I will not win by continuing that. I may sometimes but usually sooner or later I start to be on the defensive and then it is just a matter of time before I hit it out/net or give the opposing net player a weak shot that he or she can put away. So as soon as I can I just try to rush the net and if I can make that incoming volley we have some chances with 2 up.
5) If my first serve isn't going in often and my weak second serve is getting killed I try hitting an aggressive second serve as my first serve to keep my first serve percentage up. It is when they know that weak second serve is coming that they seem able to tee off on it better. I sometimes have to start mixing in a more aggressive first serve if they start to see it too often.
6) I know when I am the better player it can be disheartening when my partner double faults. I will often think just hit the serve in and I can poach this return, but then when their second serve hits the net well ok there really is nothing I can do. So again if you are having a bad serve day try to hit your safer serve first. And also if you know you are going to be the weaker partner, instead or trying to get a killer first serve that is less reliable, really focus on getting a decent reliable serve. That way you at least give your stronger partner a chance to win your service games.
Good luck.