You may be right,I don't know much about electronics. I am going to use a
DiSEqC switch for the first time when I get my new Ultra and I will use splitters with dc pass on one side for this hook up. You probably need second LNB on to power switch.
On my hook up I have now however I have never had any trouble with a regular splitter as long as LNB in second unit is turned off otherwise you get an LNB overload. The LNB is powered by the one unit.
However your way is probably the best way.
Tom