I like to make the form for the back of the bow,and use the hose on the belly side,thats just me.
About 1.25" is what I use with 2" hose,might tighten up a little for 1.5" hose. Be sure to use a metal pressure strip on top of the lams before the hose goes on or all pressure will be in center of limb.
I cut the form for the back of the bow,then figure the riser shape and cut the top 1/2 of the form for the riser(making a fake riser blank helps). Lay it all out on the bench and mark 1.25" from the bottom 1/2 up onto the top 1/2 of the form,including the riser part.
Then,dry run to make sure you can get the form bolts in with all lams in place and that everything tightens up good for best glue lines.
Good luck!! And we like pics!!