Yaker, welcome to the forum.
IMO, half the fun in having a boat is customizing it to your needs. In your case, you know the boat can easily support your combined weights. You've got 3 load bearing areas -- drive deck, cargo well and gunwales. The foredeck and afterdeck are not designed to support that much weight.
I've stood in the cargo well and also sat there as a passenger. With a piece pf plywood to distribute the load, what about a stadium seat, stool or small director's chair in that area?
If you can operate without the Mirage Drive (say with an electric motor?) why not attach a bench seat supported at the gunwales along the forward edge of the Drive deck? You could wing nut it right through the mounting boards for a quick disconnect.
If you wanted to get fancy, you could build a custom seat mount, allowing the main seat to slide back for better balance and accommodation for two (one forward).
Lots of possibilities!
