I can't do the weekend of the 4th, and can't start on a Saturday, as there is no ferry that will meet the train that day. So how about E-W on Friday 24th, setting of from Ardgay about 11.30am, back across on the Saturday 25th?
The same arrangements the following weekend would work for me too, but thereafter it is the school holidays and the Clan Gathering.
Or alternatively, and this is optimum for me but probably nobody else, have the two days as Thursday 16th and Friday 17th.