Why not split your HTML into two batches? It would be easy for you to add a "please wait" table to the top of your page and then the rest underneath - heck, if layout is important, why not split your existing table into two - with the first half containing the 'wait' message? I'm sure you could work it out!
"It sounds like your second solution may offer a possibility.." - don't make life complicated if you don't need to!