I have played with sheet to tiller steering on my contessa 26, a smaller version of your alberg, speaking in general terms. On any point of sail from reach to close hauled it works well, assuming your sails are trimmed and balanced. Off the wind I struggle a bit to maintain a course. Sheet to tiller steering is a worth while thing to play with but IMHO will be of no value when having to go forward to tend to the jib. It requires that both sails be set, balanced and trimmed.
I have two cam cleats mounted to my tiller, one on port the other on starboard. A bungee cord or light line cleated off works to lock down the tiller. See link below for an example, not the cam cleats I use but something similar.
HARKEN MICRO CAM-MATIC CAM CLEAT Binnacle.com
As others have suggested some type of tiller lock would be a decent alternative for your needs. I use a thick bungee cord locked to the tiller when going forward, not ideal but it works.
As I mentioned sheet to tiller is great idea, worth pursing, just not ideal for the task you asked about.
See the link below for more details.
Sheet-to-Tiller Self Steering