You shouldn't use ANYTHING with silicone in it to attach bulkheads, as silicone products bond weakly and leave a residue that makes it difficult to get anything else to bond to the same surface after the silicone inevitably fails. I don't know of any kayak manufacturers that use silicone products for bonding foam bulkheads; they use products like Lexel which do not contain silicone.

Another consideration is that while you can get a strong bond with adhesive-sealants on the wide surface area of foam bulkheads, a wood/glass bulkhead has very little surface area at the edges for bonding. Adhesive-sealant bonding would hold the bulkhead in place, but it would not be able to withstand any significant pressure and certainly could not be used as a footrest or as a mounting platform for a foot pump.

My suggestion is to glass it in. It's easy, it's strong and it's worth it for the peace of mind alone.