Quickfair is tough to spread, as it starts kicking off so quickly. I use Awlfair or alexseal.
Since you don't have enough air... an 8 inch pad sander works well too. I like the Makita 9227c, variable speed. It isn't as easy to run as a mud hog as the weight is balanced out of the handle... but you can do quite a bit of work mowing down known high spots with one. I say known high spots, because it will remove material just as quickly from low spots.
Treasure the sanding
pads. Anything you will use to fair something in flat, needs to always be stored with the pad facing up... and never tip the sander up at an angle. Yes you can dig down to the low on edge... but once the pad dishes out and turns convex you can no longer sand a flat surface.
To pull hull
sides I use an 18 foot 1x1 aluminum
box tube with three to four guys. One mixes and applies from the center and the two outside guys pull up. Two to three passes, filling the worst of the lows gets an 18 foot stretch of the boat "fair" but not smooth in one day. Where the box tube rides, needs to be smooth top to bottom... Think about a fair station as drawn on the plan. If it has a low spot at the station where the batten contacts, you will have a low the entire length of the batten. The verticals have to be right, where the batten contacts before you can see what is fair and what is not.
On tighter radius I use 1x1 fir battens or 3/4x1 battens in varying lengths.
yardsticks work once you get to the smaller holes or tighter radius. I like the non-anodized ones, because like the 1x1 box tube they leave black marks like pencils do on the high spots.
For a crew of 1 man, I use a pink masons string and a line of screws at the stem and transom that pulls the whole length of the boat and a bright light. Pull the string tight and every 6 inches or so along the height parallel the waterline, mark where the string touches, fill where it doesnt. This is slower than 3 guys, but the only way I've found that one man can get something perfectly fair. A light bulb out of a flourescant light fixture works well to find wee small high spots, roll it along and where it rocks and rolls is a small high. You need to get good at rocking and rolling and making an X mark with a pencil of the perfect center of rotation. Works for battens too... Wherever the furthest thing out that it contacts first defines the radius you have to build out to. If there is a small knot
to one side or the other of the ideal radius you end up fairing in a bulge.
I'll scribe a 3/4 piece of plywood
to fit where the radius is good following the pink line, cut it on the bandsaw and pull down a 4-6 foot area parallel to the waterline, and pull from where it is known good down to the waterline, if I am by myself.
Once I'm down to 1 foot wide holes, I use a 1 foot putty stiff sheet rock knife and over fill the low spots. These are the spots where the long board spans over and "won't fit." Mark them, fill them... batten and string them. I mark the entire surrounding with a pencil and keep the longboard pressure very light so I don't make a flat spot around where I filled trying to sand down to the low spot. If you take your pencil line... put it back. You may have to pull a thin "Glaze" around the whole area you sanded otherwise you end up with 1 foot square flat spots.
You can't use a DA sander and find those holes, as it fits inside them. After each puttying, use the longboard first and mark the lows.
Once you are fair in 40 grit, you can start thinking about making her smooth... 100 grit is coarse enough to fair with, but it will take you a lot longer than 40 or even 60 grit will.
I do most of the sanding
with the long boards until I have marks I can see... Once I determine something is a high spot, and not a good spot surrounded by a low... I come back with the biggest sander that will fit the radius and mow it down. 10-15 seconds... re-test with the board.
The biggest thing to think about with sanding, is to work on your timing so that you sand 10 passes before overlapping a half a pass... Or move your feet 6 inches after every 3rd long board pass over the same spot.
With machine sanding in the 40-80 grit stage on a hull
side you can go vertically, only... Overlap when you move over a half a pass... but try to do it quickly and with no pressure. Otherwise you'll dig a low line at the waterline and shear from lingering at the end of each pass, and each time you move over a half a pass.
Any bulk material removal
you do side to side will carve a low spot or flat spot along the top of the radius.
Your arms can't operate a long board very well, anything but side to side or 45 degrees down from the shear... Which spans whatever low spots get cut in on the vertical by machine sanding.
Horizontal flat spots on a radius mean your batten doesn't fit right any more as you raise and lower it... and your longboard "jumps" when it crosses the edge of the flat.
Flat spots make you think something is high to each side of it, when infact it is low... but low because it is no longer "Round" and following the same shape as the rest of the contour. This is a big distinction to make.
Always shoot for keeping 80% of the surface the same, on each sanding. Don't fill outside your lines, and sand from the good to the bad... always and forever.