Dektol has a capacity of thirty-two 8 x 10 sheets per litre of working strength solution. So each litre of normally diluted (1:2) working strength developer has enough chemical capacity to develop eight 16 x 20 sheets.
So theoretically you could mix up a litre of 1:2 solution, and then dilute it further so as to end up eventually with effectively a 1:8 solution, and still have enough capacity to develop eight 16 x 20 sheets.
I would try a test. Most likely you will be doing some test strips anyways. Try developing a smaller strip in some 1:8 developer. You will probably need something like 8 minutes developing time - maybe longer.