40 minutes ago, Hemmy said:

Most car dealers want your service more than the sell of the car.  They make more money on service than sales.  Can't imagine a boat would be any different.

I don't think it is an issue of whether a dealer would service a Malibu that was bought elsewhere -- it is how the jobs are prioritized when it's July 3 and everybody wants their boat fixed ASAP.

The parts or gasket set would set you back in the ball park of $50 for the pan/seals/timing cover and available from numerous suppliers.  If you have some tools, you could rent a cherry picker, bribe a couple of buddies with a case of cold beverages and do the job in a weekend.  You are about 2 hours of labor each way in pulling / replacing.  If it is truly only the front timing cover (which incorporates the front crank seal), you can do that in the boat.

Do you have any insight as to why it suddenly started to leak after your spring start up?  How much oil is it leaking?  Are you sure that the oil level is correct and not overfilled thus creating a leak?  Or even simpler, if there was an oil change, a spillage during the process?

Front main seal is pretty easy. 
May be kind of tight with the muffler in the way.

If it were me I'd pull your sun deck off, pull the muffler off, then get after it. 
Even if it's the timing cover it can be changed with just loosening the oil pan. 
No doubt you will be bust some knuckles a little and be in some tight spots. But doubt you need to pull the engine.  

9 minutes ago, kcpilotpat said:

I have watched several videos on aligning the coupling and it looks tedious.

No doubt, it's not a lot of fun, but when you're done you will have eliminated a fair amount of future maintenance.  Just get a nice Class D life preserver (or 2) and use that as a firm pillow to lay your chest onto against the seat rail and get comfy while you do it.  Absolutely have a helper handy since it's a bit of a pain to get in and out of position and grab tools, nuts/bolts, etc.  IIRC I had to buy a specific socket for the shaft nut. 

My only other firm advice is to use the socket trick to remove the coupler.  I bought a fairly expensive (non-refundable) coupler remover (as in this video) and due to the design of the v-drive it wouldn't fit in the area of the coupler, so that became a nice paperweight.  The alternative socket method that he mentions worked great and only cost the amount of a few bolts and nuts.  You simply put in the largest socket that will fit into the coupler and using your new longer bolts tight it up to push the shaft out.  Below is a short video to demonstrate it.

Also, while you're down there it's not a bad idea to put a wrench onto the nuts that secure the shaft log.  It's a long blind reach with very low clearance, so a ratcheting closed end wrench with a pivoting head is the ticket here; I can't recall the size.  I just happened to think to do this when I did this mod and mine were ridiculously loose. 

31 minutes ago, cowwboy said:

That seems a little steep. But I know labor can add up real quick.
Sounds like you are fairly technically capable. Removing the engine isn't very hard just kind of a nuisance removing the bulk of the interior to get to it. 
Any reason you don't want to tackle it yourself?

You say crankcase, as in oil pan gasket or is it a front / rear main seal?
The front main seal would be fairly easy in boat.

Rear main would be a little harder removing the trans and v-drive but still do-able in boat. 

I believe it's the front main/crankshaft seal or timing cover. I was told the oil pan gasket lays down in the groove in the bottom of the front cover so the engine needs to come out. Someone mentioned a speedy sleeve might be worth a try.