Klaas-
I built myself a 16' Frej which I use for day-paddles. I like it a lot. It has a skeel which may be a big part of what I like about it, BTW.
I have a few ( :-) ) boats so I wouldn't take the 16' Frej camping. I have a partly finished 'long' (18' ?) Frej in the works, which I think will hold enough gear/food/water for a few days (not few weeks) trip. The idea behind that boat was to have a boat that would be 'ideal' if I wanted to take an advanced kayak skills course which involved a few days camping and also rough water work and rolling. (The Frej is an easy boat to roll.)

I don't think that even a longer Frej will suit your weight, but Bjorn can advise better on that. If you have other boats available in your area (to rent or borrow for a few hours, or even a quick paddle at the beach) I'd advise finding a commercial boat that you like, and that fits you well. Then look for a boat to build that has similar dimensions, if you want to build something for yourself (though it will likely cost more than buying a used glass commercial boat).

My guess is that a Frej would not fit your shoe size, and once you start raising the deck more than a little, you will be losing a lot of the appeal of the design.

I wouldn't worry much about how the boat weight will affect performance on the water, though it definitely enters into the equation when thinking about getting your boat on and off the vehicle, etc. . The paddler & gear & food & water (if you are in a marine area) and how the 'baggage' is loaded will have a much bigger effect.

Nailing down your requirements more precisely will help you to zero in on a good range of boats to think about - IMO there's no boat that is a great day-paddling, or 'play' boat that would also be good for a 2 week trip without resupply.

Keep asking questions; you'll get lots of answers here.
To paraphrase an old saying: "Choose your kayak design in haste, repent at leisure!"

EDIT: Bjorn generally answers promptly, but he does go paddling and also travels when working with companies that build his designs, so there can be a few days delay. A polite follow-up is a good idea if you don't get a reply within a week, IMO.