Hello There!
In Capt. George Smith's ( Inspector of the Royal Military Academy at Woolwich) 'Universal Military Dictonary' of 1779 there are size descriptions of officers and EM tents of the period.
"TENTS, in war, a pavillion or portable house. They are made of canvas, for officers and soldiers to lie under when in the field. The sizes of the officers are not fixed; some regiments have them of one size, and some of anonther:
a captain's tent and marquee is generally 10 1/2 feet broad, 14 feet deep, and 8 feet high: the subaltern's are a foot less; the major's and the lieutenant-colonel's a foot larger; and the colonel's 2 feet larger.
The subalterns of foot lie two to a tent, and those of horse but one.
The tents of the private men are 6 1/2 feet square and 5 feet high, and hold 5 soldiers each.
The tents for the horse are 7 feet broad and 9 feet deep: they hold likewise 5 meen , and their horse accoutermants.
Bell-tents, so called for their resemblance to a bell: they serve to shelter the fire-arms from the rain.
To pitch the tents, is to fix them up ready for habitation, by the assistance of a ridge pole, two standards, and a quantity of tent-pins."
In primary source images these tents often have a rear sewn in place, often of 4 panels forming an arc. The front has two sections affixed that can be tied closed with woven tapes to give some protection to the occupants. Although there are usually 5 men assigned to a tent, 1 man per tent would probably be on rotational duty much of the time making a bit more room. In French handbooks of the period more men per tent are shown sleeping in a 'spoon' style to maximize ground space.
There do not appear to be markings, but all equipment would be marked as government property and in the period we are disscussing this would be a broad arrow over the letters B.O., for Board of Ordinance. In the 1850s this was replaced by the W.D. with broard arrow.
Remember that the tents were made of linen canvas with hemp cordage. The panels of woven canvas would normaly be about 24 inches wide so a tent 6 1/2 feet long would require 3 and a half panels joined by flat felled, or 'French' seams. These would not be the bright white that we might think, but slightly more organic looking. Also note that moldew from storage and dampness would probably make them a motteled pallett of ivory, tan, gray and gray green. The poles would probably be a weathered gray and the tent floors would be covered by straw when possible. Issue blankets of the period are often off white with a 3 to 4 inch stripe placed about the same distance from each end. These would also be stenciled with the broad arrow with the letters BO, so they cold be easily tracked if they 'went missing'.
The officers marqees were often private purchase, so there could be wide variations. One of George Washingtons tents is made of heavy, tightly woven 'Nankin' fabric from China, so it was a nice creamy yellow color. The poles on these would often be painted and in some case turned finials would be placed on the verticle pins that would project through the various eyelets in the canvas. These finials help keep the rain out and were another item that could be decorated. These might be painted in the regimental facing color: Blue for the 1st foot guards or the King's 8th, yellow for the 10th foot, black for the 64th ect.
I hope this helps...when ever possible refer to primary source materials to create plausible reconstructions. I am often dissapointed with the mistakes that are perpetuated by secondary sources in out hobby.