There are many reasons to conclude that Romans 7 cannot be about Paul the believer. I will get to the "tense" issue later, but for now I will post more material from Romans 7:
but I see a different law in the members of my body, waging war against the law of my mind and making me a prisoner of the law of sin which is in my members. 24Wretched man that I am! [Romans 7:23-24a]
As a Christian, how you be a prisoner to sin.
"how you be" one is easy. Grieve the Holy Spirit (Eph 5:18) or quench the Spirit (1 Thess5:19) is how you be.
Paul established WAY BACK in ch 6 that we make decisions (choices) of who we (belivers) present themselves to a slaves for obedience: either wickedness or righteousness. v.11-16
I could wear out the keypad on my computer posting texts that show that the believer has been set free from such bondage.
This is quite naive. Please read Rom 6:11-16 and prove that Paul wasn't telling us believers that there is a choice of who we present ourselves to for obedience.
In fact, right here in that Ephesians text, we see that believers are not imprisoned in this way:
10For we are His workmanship, created in Christ Jesus for good works, which God prepared beforehand so that we would walk in them. [Ephesians 2:10, NASB]
This verse tells us what we were created FOR; good works. It says NOTHING about being either imprisoned or set free.
Now: please explain how a person who is a "prisoner" to a law of sin can possibly do good works.
That's Paul's point exactly in Rom 6. The believer CANNOT.
btw, Eph 2:10 does NOT guarantee that the believer will perform good works. It says that's what we were created for.
And also consider this from Romans 8:
For those whom He foreknew, He also predestined to become conformed to the image of His Son, [Romans 8:29a, NASB]
No one this side of eternity will achieve this completely, because we still have a sin nature and we still sin. But this will be fulfilled fully in the resurrecton.
If Romans 7 is indeed about Paul the believer, then you need to explain to us how a man who is in the process of being conformed to the image of Jesus, is "a prisoner of the law of sin".
That's the point: when one IS in the process of being conformed, he won't be a prisoner. But not all believers participate in being conformed to the image of Jesus.
Recall what Paul said to the Galatian believers: 4:19 - My children, with whom I am again in labor until Christ is formed in you—
Now, why did he write that? He explains in v.20-21:
20but I could wish to be present with you now and to change my tone, for I am perplexed about you. 21Tell me, you who want to be under law, do you not listen to the law?
He was perplexed (confused) about them because they were turning back to the law. Recall 1:6 where he wrote this:
"I am amazed that you are so quickly deserting Him who called you by the grace of Christ, for a different gospel"
So, it's clear that not all believers participate in conforming to the image of Jesus.