Filling holes in sheet metal with a welder?

So one of my old boats has a bunch of holes in the aluminum dash and bow cover.  Its not really an option to cut out and build a new one, so I was thinking about filling them with my welder.

Problem is, filling them with my welder.  Its sheet metal so I know I can blow through it incredibly quickly and make more of a mess than I previously had.  Is it possible to use a steel backing plate or some other metal the aluminum won't stick to in order to kind of give a flat face and a heat sink to prevent disaster throughout?

The holes aren't that big, 1/4" to 1/2"

can you use the Aluminum alloy "brazing" rod ?

Probably, but it has a different color than the aluminum, so I'd like to try and avoid it for this.

In reply to Mr_Asa :

Stainless steel is the typical backer for aluminum welding. Copper is used behind steel. Basically go for a material that is a heat sink and doesn't weld to your base material or your filler.  I am not a welder, just a hack, and an engineer.  Real welders may have a better material choice or other tricks to make this job easier. 

In reply to tester (Forum Supporter) :

Try using small aluminum washers the size of the hole you want to fill. Instead of filling holes with only weld. Yes, use a backing plate  but just put a few tack welds around the washer. 

Use some of these and turn those holes into design elements

Good luck with getting a color match. Alloy and a combination of contaminants and oxidation are going to make that difficult. 

In reply to wheelsmithy (Joe-with-an-L) :

That's actually the type of nut that was on 95% of the bolts in this thing in the first place.  I'll be putting them back on all the bolts.

Problem is that most of these holes that I'm trying to fill are in random places.

My bros at work say back it with a dissimilar metal.  Stainless or copper depending on the base.  Gonna have to TIG it for anything to look decent and then blend it out.  I did stainless steel TIG with a aluminum backer and it turned out fine for my basement sink.

If its totally not replaceable, give it to a pro.  Its worth the $100.  

1. Use an aluminum backing plate. It will/might become permanent, but you may not care. 

2. Epoxy the holes up and put some high quality vinyl on top of the whole works. Fake carbon fiber, brushed aluminum, etc.