You said why weighing them is likely a waste of effort and time both.
That would not tell you much if anything.
Anyone that reshrinks a well worn box set is not beyond putting blank papers into the box instead of the true contents.
And how do you KNOW that store did the reshrink job?
IF They did do it, then they likely purchased someone else's boxes and reshrinked them for sale in the shop.
Even if they did, did they KNOW What the contents were supposed to be?

You also said you would like your listing to be accurate.
Please tell us how you plan to do that?
Do you know what is inside?
I mean other than what was SUPPOSED To be inside...
HOW can you possibly do that with something that was RESHRINKED!

PLUS you might find some treasure that does not belong...
Like a copy of Dwarven Glory some idiot stuffed into one of them...  

I saw your ad, and honestly I would rip that reshrink off them both.
I might even make a movie of it and post it for the shrink junkies to weep over...

It is obvious both boxes have a good bit of wear on them.
Might as well confirm the contents and then sell them as they are with all openness.

At least that would be my move.

Well, they sure look reshrinked to me. I would open them both up.

SF has a bunch of stuff and sometimes the counters are gone or one of the books or map is gone.

Top Secret is almost always missing the dice. You will also need to see if the Top Secret is actually a first print. You can do that by looking at the rulebook. If it has the wizard logo (like the picture on the back of the box), it is a first print. First prints, believe it or not, are generally pretty hard to come by. The second print has same box but TSR face logo on rule book, and no, they did not change the picture on the back of the box. The second prints are common as hell. The third print has the face logo on the box as well as the rule book.

I appreciate all the advice.  I took off the shrink.  If it's O.K. with the Alabama man, it must be O.K.  Inside Star Frontiers I found:

CONTENTS:
• Basic Game Rules booklet (16 pages)
• Expanded Game Rules booklet (60 pages)
• Module SF-0: Crash on Volturnus (30 pages) with cover folder/map.
• Fold-out, double-sided city/building map
• 300 counters (1 sheet) UNPUNCHED!
• Complete series of fine TSR Products sheet
• TSR Feedback Form
• RPGA Application
• RPGA Application yellow envelope

I think this one is complete!  And near mint!  Yay!

Then I opened up Top Secret.

CONTENTS:
• Basic Game Rules booklet (64 pages) Dossier page removed but present
• Module (28 pages) with cover folder/map. Interior mission briefing removed from staples but present
• 15 photocopies of Agent Dossier (added in and not original)
• RPGA Application
• RPGA Application yellow envelope
• 2 d20 Dice!    But obviously used.    One pink and one white.

I think this is complete, but I'm not sure.  No writing or highlighting, but some staple rust makes this probably fine condition overall.

Are these complete as far as you know?

EDIT: Top Secret was 2nd print.