If your looking for a quick deploy antenna, go elevated. I would use a 5/8 design that doesn't require radials, and choke the coax both at about a foot below the feed point and about 9 feet below the feed line. Yep, I said it, two chokes. Also, if you have a mast, make the part the antenna it attaches to non-conductive.
Elevated horizontal radials essentially do two things, they help lower the feed point impedance, making it easier to match, and if they are near 1/4 wavelength they also act like an RF trap, having an effect much like a choke. Shorter radials will only have an effect on the feed point impedance, and even with that it will be less of an effect than full size 1/4 wavelength radials, even if you have more of them. All 5/8 wavelength antennas require some form of matching, they do not have a naturally low feed point impedance. You could use 3/8 wavelength radials to counter the 5/8 wavelength element's reactance, but even then your going to need something to raise the impedance to between 200 and 400 ohms, a matching circuit, or perhaps a 4:1 unun?
Angling elevated radials down on a 5/8 wavelength antenna is also not a good thing. If they are horizontal the RF from the radials will cancel. However if they are angled down, some of the RF on the radials will radiate, and that radiated RF will be out of phase with the part of the antenna that benefits you the most, which will raise you angle of radiation. As 5/8 wavelength is already near the upper length limit when it comes to maintaining a low angle of radiation, any radiation from radials that are angled down will not be beneficial to the antenna.
When it comes to ground mounting the antenna, the radials act very differently than elevated radials. You already have a ground present in the earth, although it is a crappy ground, it does exist. In this case, the radials directly affect the efficiency of the antenna by increasing the quality of the earth in the vicinity of the antenna. The radials are not the entire ground system as RF currents exist beyond the radials in said earth. Essentially the more radials in this case the better. Twice as many 1/8 wavelength radials is better than half as many 1/4 wavelength radials. You could also put down a "ground screen" or a roll of chicken wire or something and attach the ground side of the feed line to it and still get a very good results. Any which way, to maintain a good efficiency, you would need a lot of radials, which will take time to set up and take down. Also, many people will add radials to a ground mounted antenna until the SWR stops going down, then they will stop as SWR then starts going up again. If this were a permanent mounted antenna I would say don't make this mistake. If adding more radials is still affecting SWR, then adding more radials is making the antenna more and more efficient. SWR is not a measure of how efficient an antenna is, just how well it is matched to the feed line. A lot of people will use about 20 radials, and others will insist on using 32, or even 64 or more (or double those numbers if you are using 1/8 wavelength radials). Long story short, the number of radials used on this type of antenna directly affects how well it will perform, which means you will need to take the time and set up all and take down of those radials every time, which imho, kills the idea of a quick deploy antenna. When mounted on the earth, 4 radials is simply not enough.
When it comes to antenna performance, a t2lt mounted at the same tip height as a 5/8 wavelength antenna will perform about the same as said 5/8 wavelength antenna. If the 5/8 "sh*ts all over* any other antenna antenna mounted at the same tip height, then the other antenna has a problem that needs to be fixed. The great secret to antenna performance isn't in the antenna's length, it is in the height of the antenna's current node, which in a vertical is electrically 1/4 wavelength down from the antenna's tip. All the length of a longer antenna does is raise this current node higher than on a shorter antenna (assuming the same mounting height), and it actually does it at a cost. In this case, the t2lt mounted at the same tip height will have a *slight* advantage when it comes to local contacts and the 5/8 will have a *slight* advantage when it comes to DX contacts. You will not I put astrics around the word "slight". If its so much that you notice much of a difference then you have a problem with one of the antennas being tested.
The DB
