i think a gas gauge is a pretty worthwhile instrument to have.  being stranded in the middle of a lake/river because you didnt know how much gas you had = dumb.  not to mention the feeling you're gonna have when u have to rope someone into towing you. 

i dont think drilling a hole in the dash is too much work, we're talking what... 30 mins max with a drill from home depot?  then mounting and running a few wires around to the sending unit(s). its winter time, put it on the project list.

   Lets just say you decide pull the trigger and put a gas gauge in, your running two tanks one sending unit will work OK but not going to be accurate even if their pulling equal, and if one pulls more then the other and ones of the tanks goes empty now you have air in the tank = stranded back to square one,or you can run a manual shut off valve to keep from pulling air after it goes empty.

From reading all the replies so far, it sounds like the general consensus is that having a gauge is a matter of personal preference. Cutting a hole and wiring up a gauge is a pretty simple task. However, as I stated before, only the left tank has a sening unit and by the looks of it cannot be seviced unless the tank is removed. I think it would be pretty pointless to go thru the trouble of getting that sending unit to work and not be able to read the level in both tanks. The way I see it, I have 2 options: A) Remove both tanks and run wiring for two senders then install a 2 way switch. Or B) Carry a stick in my boat and manually check the fuel level. I don't know what's involved in removing and reinstalling both fuel tanks, but it doesn't look easy. This is something that I'm going to have to think about for a while. Thanks for the replies.