I've had good success brushing on a coat of zinc chromate primer and then using a coat of "Hammerite" paint on bare aluminum. I don't know if if Hammerite is available in your area, but it is a glass-filled enamel that creates a very slick surface and is quite durable. It also fills well and hides a multitude of sins. For "slick strips" I've used ultra-high density polyethylene. UHMD tends to be an expensive material, but I found a place that sells UHMD cutting boards for far less than I can buy the stuff in sheet form.
The difficulty with sanding aluminum -- or dealing with abrasion on untreated aluminum of any form, is that you will create a lot of aluminum oxide. Aluminum oxide is nasty stuff.
There's some debate as to its toxicity. Some say it's relatively innocuous, and others claim it will make you want to run for president on the US Republican ticket. It creates a dark and very durable black stain on anything that it touches, and is practically impossible to remove. It's not soluble in water, nor any other compound that I've tried. It will eventually come off skin with forceful application of pumice soap, along with a few layers of hide.
I've not built my junk rig yet. This comes from doing a few masts on other boats, restoring a 1972 Land Rover, and doing a little work on a 1956 Cessna aircraft that had a mouse nest in the tail. Mouse pee is right up there with nitric acid for pure corrosion potential.
If you are going to sand your stick, please, get a very good dust mask, eye protection, gloves and some Tyvek suits. There's a barrier cream sold under the brand name "Liquid Gloves" here in the US. Despite the gloves moniker, you can use it on your face or any other exposed skin, and it makes it a little bit easier to get the oxide off.