I have to agree with Foodstick about there being too many formers. I went over to Outerzone and had a look at the plans and construction article. One option would be to source an "Adjusto-Jig". They are scarce but there are apparently a few out there. Failing that, you could recreate the function of an adjusto-jig without the adjusto by cutting a series of plywood slotted tongues and gluing them to a base along a straight datum line. The slots would have to be narrow enough to hold the "fuselage crutch" stringers in place while the formers and eventually the sheeting were glued in place. It would be necessary to be really accurate in locating and marking the position of the formers on the crutches and in locating the crutches in relation to one another. It might be easier to add a set of stingers at about the level of the fuselage floor and use them as a crutch for building the fuselage.