I went with a Vltor modstock on my M1A scout several years ago, for much of the same reasons you mentioned.
I dont' really think there is enough clearance on the underside of the forend for mounting a long rail. Maybe, but it seems pretty tight between the inisde of the stock and the working bits.
The Vltor stock does not come with a top heat shield or a forward sling mount (At least mine didn't.)
I installed this short rail/sling point; which works quite well for my needs. Gives me room to mount a bipod if desired.
Since the Vltor stocks are built form GI fiberglass stocks, maybe you could pick up one of those cheap to do a little R+D?