LTT OVERSHOT ASSIGNED ALT DURING CLB.

Narrative

ATC CLRNC SPECIFIED DIRECT JINGO INTXN; DIRECT SAC; CAP 02 ARR TO SJC. MAINTAIN 4000 FT (THE MOST COMMON CLRNC GIVEN TO US ON THIS RTE IS DIRECT SAC; MAINTAIN 11000 FT). THIS WAS THE SIXTH LEG OF OUR DAY. FLYING IN CONSTANT ICE AND TURB DUE TO A FRONTAL SYS MOVING THROUGH NORTHERN CA AND SOUTHERN OR. MOST OF THE LEGS WERE FLOWN IN CONSTANT IMC; AND WE HAVE NO AUTOPLT; SO IT IS NORMAL TO BE QUITE TIRED TOWARD THE END OF OUR 8 LEG; 11 HR DAY. DURING THE PRE-DEP BRIEFING; I NOTED THE 4000 FT ALT RESTRICTION. UPON TKOF; CIC TWR REQUESTED A BASE RPT FROM US. DURING CLBOUT; I DO NOT RECALL HEARING THE FO CALL THE MANDATORY '1000 FT TO GO' AND '300 FT TO GO' ALT CALLS. SINCE WE HAVE NO ALT ALERTER; I WAS NOT REMINDED OF MY LEVEL-OFF ALT. UNFORTUNATELY; I LET MYSELF BECOME DISTRACTED BY HELPING THE FO ESTIMATE THE CLOUD BASES; IN ORDER TO TELL CTR SO THEY COULD RELAY THE INFO TO CIC TWR. CLBING THROUGH 5300 FT; CTR ASKED US OUR ALT AND I REALIZED I HAD BUSTED MY 4000 FT LIMIT. I QUICKLY STOPPED MY CLB AND ASKED OAKLAND IF THEY WANTED ME BACK TO 4000 FT. THE CTLR REPLIED NO AND DIRECTED US TO CONTINUE CLB TO 11000 FT. HAD I MAINTAINED PROPER STERILE COCKPIT DISCIPLINE AND NOT BECOME DISTRACTED BY TRYING TO ESTIMATE THE CLOUD BASES; I WOULD HAVE RECOGNIZED MY LEVEL-OFF ALT AND THE DEV WOULD NOT HAVE OCCURRED. I ALSO FIRMLY BELIEVE THAT AN ALT ALERTER WOULD HAVE PREVENTED THIS DEV. I BELIEVE THE FAA SHOULD REQUIRE ALERTERS IN ALL SCHEDULED AIRLINE ACFT; NOT JUST THOSE OVER 30 SEATS. IF WE WAIT FOR THE AIRLINES TO INSTALL THEM OF THEIR OWN VOLITION; IT WILL NEVER HAPPEN; BECAUSE IT CUTS INTO PROFITS. I ALSO BELIEVE WE NEED MORE STRINGENT REGS PERTAINING TO CREW DUTY AND REST TIMES. I REGULARLY FLY 12-15 HR DUTY DAYS; UP TO 12 LEGS AND 8 HRS OF FLT TIME. BY THE END OF A DAY IN WHICH IFR CONDITIONS PREVAIL; I AM PHYSICALLY EXHAUSTED; AND THE POTENTIAL FOR MISTAKES EXISTS.