Checking with a ‘39 owner, he says his boat is actually 39’ not counting the bow pulpit and swim platform. Including both it is 42’. If you hinged the platform, you’d have to chain or cable each side (like a tailgate) and it need to be spaced out a few inches to account for the curve and aft lean of the transom, and you would loose the transom door access while the platform was raised. A reinforcing rib would need to be added beneath the platform to withstand the center stresses.
Of course, hinging the bow pulpit would likely require some forethought regarding anchor repositioning when folded and some pretty substantial reinforcement. All this is manageable if one has the skills or $$$. Best of luck.
"When life gets hard, eat marshmallows”.